Phase modulating apparatus and phase modulating method

ABSTRACT

An adder unit reads a desired CGH pattern from a pattern memory unit and a phase distortion correction pattern from a distortion-correction pattern memory unit and adds both patterns together to generate a phase distortion corrected pattern. A control unit controls a phase modulation module in accordance with the phase distortion corrected pattern. Accordingly, phase-modulated light based on the desired phase pattern can be generated precisely, easily and quickly.

This is a Division of application Ser. No. 10/493,464 filed May 12,2004, which in turn is a National Phase of Application No.PCT/JP02/11115 filed Oct. 25, 2002. The disclosures of the priorapplications are hereby incorporated by reference herein in theirentirety.

BACKGROUND

The present invention relates to a phase modulating apparatus, a phasemodulating method, a program for performing the phase modulating method,and a recording medium in which the program is recorded. Moreparticularly, the invention relates to a phase modulating apparatus andphase modulating method for modulating the phase of a laser beam byusing a phase modulated spatial light modulator, a program forperforming the phase modulating method, and a recording medium in whichthe program is recorded.

There has been proposed a phase modulating apparatus that uses a phasemodulated spatial light modulator to modulate the phase of a laser beamin accordance with a phase pattern calculated by a computer. In thephase modulating apparatus, a phase pattern is written to the phasemodulated spatial light modulator to be irradiated by a laser beam, sothat phase modulation light modulated with the phase pattern isgenerated.

Japanese Patent No. 2,785,427 describes a method of modulating the phaseand intensity of light by utilizing a TN-liquid-crystal spatiallight-modulating element. In this method, a phase pattern to bedisplayed on the TN-liquid-crystal spatial light modulating element isformed in consideration of the phase distortion that occurs due to thedrive voltage applied across the TN liquid-crystal.

SUMMARY

In the case a phase modulating apparatus is provided with a laser lightsource, a phase modulated spatial light modulator, and an optical systemfor guiding a laser beam, phase-modulated light having a phase patterndifferent from the expected may be generated if any phase distortion isinduced in the laser beam by the laser light source, the phase modulatedspatial light modulator, or the optical system for guiding the laserbeam.

Accordingly, an attempt to reduce the phase distortion is performed byassembling an expensive optical system, or improving the flatness of thesubstrate provided on the reading side of the phase modulated spatiallight modulator.

In order to manufacture a phase modulated spatial light modulator thathas a reading-side substrate with high flatness, expensive materialsmust be used, which makes manufacture of the spatial light modulatordifficult. Consequently, the manufacturing cost is very high. This makesit difficult to mass-produce the phase modulating apparatus.

As described in Japanese unexamined patent application publication No.10-186283, an output image generated with phase-modulated light isdetected, and a phase modulated spatial light modulator isfeedback-controlled based on the detected result. Accordingly, a nearlyideal output image is formed by compensating the characteristicdisplacement of the entire optical system.

According to the image-forming method disclosed in Japanese unexaminedpatent application publication No. 10-186283, the feedback loop must berepeated until a desired output image is obtained, which takes much timeto generate the output image. In practice, the output image undergoesrandom fluctuation because of the changes in the light source. If therandom fluctuation is detected together with the fluctuation inherent tothe feedback control, it is substantially difficult to perform anaccurate feedback control.

The present invention has been made to solve the problems describedabove. An object of the invention is to provide a phase modulatingapparatus that can phase-modulate light in accordance with a desiredphase pattern accurately, easily, and quickly.

Another object of the invention is to provide a phase modulatingapparatus that can be manufactured at lower cost.

Further object of the invention is to provide a phase modulating methodthat can phase-modulate light in accordance with a desired phase patternaccurately, easily and quickly.

Still further object of the invention is to provide a program that canperform the above phase modulating method and a recording medium thatstores the program.

In order to accomplish the above objects, the present invention ischaracterized by a phase modulating apparatus including: a light sourcethat emits light; adding means that adds a desired phase pattern and awavefront-distortion correction phase pattern for correcting thewavefront distortion of the light in order to generate a distortioncorrected phase pattern; and an electrically-addressed phase modulatedspatial light modulator that phase-modulates the light in accordancewith the distortion corrected phase pattern. When a sum of the desiredphase pattern and the wavefront-distortion correction phase pattern hasa negative value or a value equal to or more than 2π, the adding meansgenerates a remainder obtained by dividing the sum by 2π as thedistortion corrected phase pattern.

In the present invention, the wavefront-distortion correction phasepattern for correcting the wavefront distortion and the desired phasepattern are prepared separately from each other. These patterns are thenadded together to generate a wavefront-distortion corrected phasepattern. Then, the electrically-addressed phase modulated spatial lightmodulator is driven in accordance with the wavefront-distortioncorrected phase pattern. It is possible to phase-modulate light withoutlight distortion being corrected by using the desired phase patternprecisely. Since the wavefront-distortion correction phase pattern forcorrecting the wavefront distortion and the desired phase pattern areadded together, the apparatus can have a simple configuration togenerate the wavefront-distortion corrected pattern within a short time.Hence, the phase modulating apparatus according to the present inventioncan perform a real time control and be manufactured at lower cost.

Preferably, the wavefront-distortion correction phase pattern includes aphase pattern generated by inverting a sign of a wavefront distortionphase pattern indicating the wavefront distortion of the light. Thewavefront distortion can be reliably corrected, because thewavefront-distortion correction phase pattern is generated by invertingthe sign of the wavefront-distortion phase pattern.

When a phase value obtained by adding the desired phase pattern and thewavefront-distortion correction phase pattern has a negative value or avalue equal to or greater than 2π, the adding means generates aremainder obtained by dividing the phase value by 2π as the distortioncorrected phase pattern. To find the remainder obtained by dividing thenegative value of the phase value by 2π, it is sufficient to determinethe absolute value of the negative value and find a minimum positivevalue such that the sum of the absolute value and the minimum positivevalue equal an integral multiple of 2π. When the sum of the desiredphase pattern and the wavefront-distortion correction phase pattern hasa negative value or a value equal to or greater than 2π, the remainderobtained by dividing the sum by 2π is generated as the distortioncorrected phase pattern. Therefore, even if the electrically-addressedphase modulated spatial light modulator has no ability to perform phasemodulation on light having more phase modulation amount than 2π, theelectrically-addressed phase modulated spatial light modulator canperform phase modulation on a phase value, i.e., the remainder obtainedby dividing the sum by 2π. Thus, by performing phase modulation on thereminder, the apparatus is considered to perform phase modulation on aphase value equal to or greater than 2π.

Preferably, a phase modulating apparatus of the present inventionfurther includes storing means that stores the wavefront-distortioncorrection phase pattern. The adding means reads thewavefront-distortion correction phase pattern from the storing means andthen adds the wavefront-distortion correction phase pattern to thedesired phase pattern.

Since the wavefront-distortion correction phase pattern is stored, thewavefront-distortion corrected phase pattern can be generated merely byreading the wavefront-distortion correction phase pattern and adding itto the desired phase pattern. The wavefront-distortion corrected phasepattern can be therefore generated within a short time.

In this case, it is preferable that the phase modulating apparatus ofthe invention has holding a means that holds the desired phase patternin advance. The adding means reads the desired phase pattern and thewavefront-distortion correction phase pattern individually and adds themtogether to generate a wavefront-distortion corrected phase pattern.Therefore, it is possible to generate the wavefront-distortion correctedphase pattern within a short time.

A phase modulating apparatus according to the present invention includesa light source that emits light; adding means that adds a desired phasepattern and a wavefront-distortion correction phase pattern forcorrecting wavefront-distortion of the light in order to generate adistortion corrected phase pattern; an electrically-addressed phasemodulated spatial light modulator that phase-modulates the light inaccordance with the distortion corrected phase pattern; measuring meansthat optically measures the wavefront distortion of the light in orderto generate the wavefront-distortion phase pattern indicating thewavefront distortion; and generating means that inverts a sign of thewavefront-distortion phase pattern in order to generate thewavefront-distortion correction phase pattern. The wavefront-distortioncorrection phase pattern can be generated merely by measuring thewavefront distortion and then inverting the sign of this distortion.Accordingly, any complex computation is not necessary. And, thewavefront-distortion correction phase pattern can be quickly obtained athigh precision. In addition, the wavefront-distortion correction phasepattern can be easily generated independently of the desired phasepattern.

A phase modulating apparatus according to the present invention furtherincludes input means that receives the wavefront-distortion correctionphase pattern. The adding means adds the received wavefront-distortioncorrection phase pattern to the desired phase pattern. Awavefront-distortion corrected phase pattern can be generated merely byadding the received wavefront-distortion correction phase pattern to thedesired phase pattern. Accordingly, the wavefront-distortion correctedphase pattern can be generated within a short time.

A phase modulating apparatus according to the present invention includesa light source that emits light; adding means that adds a desired phasepattern and a wavefront-distortion correction phase pattern forcorrecting wavefront-distortion of the light in order to generate adistortion corrected phase pattern; and electrically-addressed phasemodulated spatial light modulator that phase-modulates the light inaccordance with the distortion corrected phase pattern; measuring meansthat optically measures the wavefront distortion of the light in orderto generate the wavefront-distortion phase pattern indicating thewavefront distortion; and generating means that inverts a sign of thewavefront-distortion phase pattern in order to generate thewavefront-distortion correction phase pattern. The wavefront-distortioncorrection phase pattern can be generated merely by measuring thewavefront distortion and then inverting the sign of this distortion.Accordingly, any complex computation is not necessary. And, thewavefront-distortion correction phase pattern can be quickly obtained athigh precision. In addition, the wavefront-distortion correction phasepattern can be easily generated independently of the desired phasepattern.

In this case, preferably, the measuring means repeats measurement of thewavefront distortion of the light in order to generate thewavefront-distortion phase pattern that indicates the wavefrontdistortion. The generating means inverts a sign of thewavefront-distortion phase pattern to generate the wavefront-distortioncorrection phase pattern, every time the measuring means measures thewavefront distortion of the light. The adding means adds thewavefront-distortion correction phase pattern to the desired phasepattern in order to renew the wavefront-distortion corrected phasepattern, every time the generating means generates thewavefront-distortion correction phase pattern. Theelectrically-addressed phase modulated spatial light modulatorphase-modulates the light in accordance with the renewed distortioncorrected phase pattern repeatedly.

A dynamic wavefront distortion as well as a static wavefront distortioncan be measured in real time, so that it is possible to generate awavefront-distortion correction phase pattern that can correct a lot oftypes of wavefront distortion containing a dynamic distortion. Thus,phase-modulated light can be generated at high precision.

In the case, the phase modulating apparatus of the present invention hasa holding means that holds the desired phase pattern beforehand, theadding means reads the desired phase pattern from the holding means andthen adds it to the wavefront-distortion correction phase pattern whichis repeatedly generated, thereby renewing the wavefront-distortioncorrected phase pattern repeatedly. Accordingly, it is possible toprecisely generate phase-modulated light with the wavefront-distortioncontaining a dynamic distortion component being corrected. In the casethe phase modulating apparatus of the present invention has a means forgenerating a desired pattern, the adding means adds the generateddesired phase pattern to the wavefront-distortion correction phasepattern repeatedly generated, thereby renewing the wavefront-distortioncorrected phase pattern. Thus, it is possible to generatephase-modulated light with the wavefront-distortion containing a dynamicdistortion component being corrected.

The electrically-addressed phase modulated spatial light modulator hasan input/output surface to receive and emit the light therethrough. Thewavefront-distortion correction phase pattern includes a phase patternfor correcting the wavefront distortion of the light induced by theinput/output surface. High-precision phase modulation can beaccomplished by correcting the wavefront distortion of light induced bythe input/output surface of the electrically-addressed phase modulatedspatial light modulator.

In this case, it is preferable that the wavefront-distortion correctionphase pattern is generated by inverting a sign of thewavefront-distortion phase pattern that indicates the wavefrontdistortion of the light emitted from the input/output surface of theelectrically-addressed phase modulated spatial light modulator which isnot driven. According to the wavefront-distortion correction phasepattern, the wavefront distortion induced by the input/output surface ofthe electrically-addressed phase modulated spatial light modulator thatis driven to generate a desired phase pattern can be corrected among thewavefront distortions of the light emerging from the input/outputsurface.

In this case, preferably, a phase modulating apparatus according to thepresent invention further includes a first optical component that guidesthe light emitted from the light source to the input/output surface ofthe electrically-addressed phase modulated spatial light modulator. Inthis apparatus, the electrically-addressed phase modulated spatial lightmodulator has the input/output surface which the light impinges on oremerges from. The wavefront-distortion correction phase pattern includesa phase pattern for correcting the wavefront distortion of the lightinduced by at least one of the light source, the input/output surface ofthe electrically-addressed phase modulated spatial light modulator, andfirst optical component. High-precision phase modulation can beachieved, because the wavefront distortion of light induced by one ormore of the optical components constituting the phase modulatingapparatus can be corrected.

In this case, it is preferable that the wavefront-distortion correctionphase pattern includes a phase pattern generated by inverting a sign ofthe wavefront-distortion phase pattern indicating the wavefrontdistortion of the light induced by at least one of the light source, theinput/output surface of the electrically-addressed phase modulatedspatial light modulator, and the first optical component. Since thewavefront-distortion correction phase pattern is generated by invertingthe sign of the wavefront-distortion phase pattern, the wavefrontdistortion of light can be reliably corrected. Note that thewavefront-distortion correction phase pattern can be obtained bymeasuring the wavefront distortion induced by one or more of theinput/output surface of the electrically-addressed phase modulatedspatial light modulator, the light source, and the first opticalcomponent.

When a phase modulating apparatus according to the present inventionincludes a second optical component that guides the light emerging fromthe input/output surface of the electrically-addressed phase modulatedspatial light modulator, it is preferable that the wavefront-distortioncorrection phase pattern includes a phase pattern for correcting thewavefront distortion of the light induced by at least one of the lightsource, the input/output surface of the electrically-addressed phasemodulated spatial light modulator, the first optical component, and thesecond optical component. Phase modulation of higher precision can beachieved, because the wavefront distortion of light induced with one ormore of the optical components constituting the phase modulatingapparatus can be corrected.

For example, if the wavefront-distortion correction phase pattern is forcorrecting the wavefront distortion of light induced by all opticalcomponents constituting the phase modulating apparatus, phase modulationof higher precision can be accomplished.

In this case, it is preferable that the wavefront-distortion correctionphase pattern includes a phase pattern generated by inverting a sign ofthe wavefront-distortion phase pattern indicating the wavefrontdistortion of the light induced by at least one of the light source, theinput/output surface of the electrically-addressed phase modulatedspatial light modulator, the first optical component and the secondoptical component. Since the wavefront-distortion correction phasepattern is generated by inverting the sign of the wavefront-distortionphase pattern, the wavefront distortion of light can be reliablycorrected. Note that the wavefront-distortion phase pattern is obtainedby measuring the wavefront distortion of light induced by one or more ofthe input/output surface of the electrically-addressed phase modulatedspatial light modulator, the light source, the first optical component,and the second optical component together.

Alternatively, it is preferable that the wavefront-distortion correctionphase pattern includes at least one of a first wavefront-distortioncorrection phase pattern for correcting the wavefront distortion inducedby the input/output surface of the electrically-addressed phasemodulated spatial light modulator, a second wavefront-distortioncorrection phase pattern for correcting the wavefront distortion inducedby the light source, and a third wavefront-distortion correction phasepattern for correcting the wavefront distortion induced by the firstoptical component. The adding means adds at least one of the first,second, and third wavefront-distortion correction phase patterns to thedesired phase pattern in order to generate a distortion corrected phasepattern. The wavefront distortion of light induced by one or more of theoptical components constituting the phase modulating apparatus can becorrected merely by adding one or more of the first to thirdwavefront-distortion correction phase patterns to the desired phasepattern.

In this case, it is preferable that the first wavefront-distortioncorrection phase pattern includes a phase pattern generated by invertinga sign of a wavefront-distortion phase pattern indicating the wavefrontdistortion induced by the input/output surface of theelectrically-addressed phase modulated spatial light modulator. It ispreferable that the second wavefront-distortion correction phase patternincludes a phase pattern generated by inverting a sign of awavefront-distortion phase pattern indicating the wavefront distortioninduced by the light source. It is preferable that the thirdwavefront-distortion correction phase pattern includes a phase patterngenerated by inverting a sign of a wavefront-distortion phase patternindicating the wavefront distortion induced by the first opticalcomponent. Since each wavefront-distortion correction phase pattern isgenerated by inverting the sign of the wavefront-distortion phasepattern, the wavefront distortion of light can be reliably corrected.Note that each wavefront-distortion phase pattern can be obtained bymeasuring the wavefront distortion of light induced by the correspondingoptical component.

For example, preferably, a first wavefront-distortion correction phasepattern is generated by inverting a sign of a wavefront-distortion phasepattern indicating the wavefront distortion of the light induced by theinput/output surface of the electrically-addressed phase modulatedspatial light modulator. A fourth wavefront-distortion phase pattern isgenerated by inverting a sign of a wavefront-distortion correction phasepattern indicating the wavefront distortion of the light induced by thelight source and the first optical component. The adding means adds thefirst wavefront-distortion correction phase pattern and the fourthwavefront-distortion phase pattern to the desired phase pattern in orderto generate the distortion corrected phase pattern. The wavefrontdistortion of light induced by the input/output surface of theelectrically-addressed phase modulated spatial light modulator, thelight source, and the first optical component can be corrected merely byadding the first wavefront-distortion correction phase pattern and thefourth wavefront-distortion correction phase pattern to the desiredphase pattern.

In this case, it is preferable that a phase modulating apparatusaccording to the present invention further includes input means thatreceives a first wavefront-distortion correction phase pattern generatedby inverting a sign of a wavefront-distortion phase pattern indicatingwavefront distortion of light emitted from the input/output surface ofthe electrically-addressed phase modulated spatial light modulator whichis not driven. The apparatus includes storing means that stores thefirst wavefront-distortion phase pattern. The measuring means includesdistortion measuring means that measures the wavefront distortion of thelight induced by the light source and the first optical component inorder to generate a wavefront-distortion phase pattern that indicatesthe wavefront distortion. The generating means includes patterngenerating means that inverts the sign of the wavefront-distortion phasepattern in order to generate the fourth wavefront-distortion correctionphase pattern. The adding means adds the first and the fourthwavefront-distortion correction phase patterns to the desired phasepattern in order to generate the distortion corrected phase pattern.

The fourth wavefront-distortion correction phase pattern can begenerated by only inverting the sign of the wavefront-distortion phasepattern indicating the wavefront distortion of light induced by thelight source and the first optical component. Hence, the wavefrontdistortion of light induced by the light source, the first opticalcomponent, and the input/output surface of the electrically-addressedphase modulated spatial light modulator can be corrected merely byadding the fourth wavefront-distortion correction phase pattern andfirst wavefront-distortion correction phase pattern to the desired phasepattern.

In this case, the distortion measuring means repeats measurement of thewavefront distortion of the light induced by the light source and thefirst optical component to repeatedly generate a wavefront-distortionphase pattern indicating the wavefront distortion. The patterngenerating means inverts a sing of the wavefront-distortion phasepattern to repeatedly generate the fourth wavefront-distortioncorrection phase pattern. The adder means adds the repeatedly generatedforth wavefront-distortion correction phase pattern and the firstwavefront-distortion correction phase pattern to the desired phasepattern to repeatedly renew the wavefront-distortion corrected phasepattern. The electrically-addressed phase modulated spatial lightmodulator phase-modulates the light in accordance with the repeatedlyrenewed distortion corrected phase pattern.

A phase modulating apparatus according to the present invention includesa light source that emits light; adding means that adds a desired phasepattern and a wavefront-distortion correction phase pattern forcorrecting wavefront-distortion of the light in order to generate adistortion corrected phase pattern; and an electrically-addressed phasemodulated spatial light modulator that phase-modulates the light inaccordance with the distortion corrected phase pattern. Theelectrically-addressed phase modulated spatial light modulator includesa reflective type of phase modulated spatial light modulator.

The present invention provides a phase modulating method including:providing a desired phase pattern; providing a wavefront-distortioncorrection phase pattern for correcting a wavefront distortion of light;adding the desired phase pattern to the wavefront-distortion correctionphase pattern in order to generate a distortion corrected phase pattern;and phase-modulating the light by driving an electrically-addressedphase modulated spatial light modulator in accordance with thedistortion corrected phase pattern. When a sum of the desired phasepattern and the wavefront-distortion correction phase pattern has anegative value of a value equal to or more than 2π, a remainder obtainedby dividing the sum by 2π is generated as the distortion corrected phasepattern in the step of adding.

According to the present invention, a wavefront-distortion correctionphase pattern for correcting wavefront distortion and a desired phasepattern are prepared separately from each other to add them together,thereby generating a wavefront-distortion corrected phase pattern. Thewavefront-distortion corrected phase pattern is used to drive theelectrically-addressed phase modulated spatial light modulator. Thus,light phase-modulated with the desired phase pattern can be generatedprecisely with the wavefront distortion being corrected. In addition,the wavefront-distortion corrected phase pattern can be easily generatedwithin a short time merely by adding the wavefront-distortion correctionphase pattern and the desired phase pattern together.

A phase modulating method of the present invention includes providing adesired pattern; providing a wavefront-distortion correction phasepattern for correcting a wavefront distortion of light; adding thedesire pattern to the wavefront-distortion correction phase pattern togenerated a distortion corrected phase pattern; and phase-modulating thelight by driving an electrically-addressed phase modulated spatial lightmodulator in accordance with the distortion corrected phase pattern. Theproviding the wavefront-distortion correction phase pattern includes:measuring the wavefront distortion of the light optically and generatingthe wavefront-distortion phase pattern indicating the wavefrontdistortion; and inverting a sign of the wavefront distortion phasepattern in order to generate the wavefront-distortion correction phasepattern. The adding includes adding the generated wavefront-distortioncorrection phase pattern to the desired phase pattern. Thewavefront-distortion correction phase pattern can be generated merely bymeasuring the wavefront distortion and then inverting the sign thereof.Hence, complex computation is not necessary, so that thewavefront-distortion correction phase pattern can be obtained easily andfast.

In this case, it is preferable that the providing a wavefront-distortioncorrection phase pattern includes: receiving the wavefront-distortioncorrection phase pattern. The adding includes adding the receivedwavefront-distortion correction phase pattern to the desired phasepattern. The wavefront-distortion corrected phase pattern can begenerated merely by adding the received wavefront-distortion correctionphase pattern to the desired phase pattern, so that thewavefront-distortion corrected phase pattern can be generated quickly.

A phase modulating method of the present invention includes providing adesired pattern; providing a wavefront-distortion correction phasepattern for correcting a wavefront distortion of light; adding thedesired pattern to the wavefront-distortion correction phase pattern togenerate a distortion corrected phase pattern; and phase-modulating thelight by driving an electrically-addressed phase modulated spatial lightmodulator in accordance with the distortion corrected phase pattern. Theproviding the wavefront-distortion correction phase pattern includes:measuring the wavefront distortion of the light optically and generatingthe wavefront-distortion phase pattern indicating the wavefrontdistortion; and inverting a sign of the wavefront distortion phasepattern in order to generate the wavefront-distortion correction phasepattern. The adding includes adding the generated wavefront-distortioncorrection phase pattern to the desired phase pattern. Thewavefront-distortion correction phase pattern can be generated merely bymeasuring the wavefront distortion and then inverting the sign thereof.Hence, complex computation is not necessary, so that thewavefront-distortion correction phase pattern can be obtained easily andfast.

In this case, the measuring includes repeating measurement of thewavefront distortion of the light in order to generate a wavefrontdistortion phase pattern indicating the wavefront distortion. Theinverting includes inverting a sign of the wavefront distortion phasepattern, thereby repeatedly generating the wavefront-distortioncorrection phase pattern. The adding includes repeatedly adding thewavefront-distortion correction phase pattern, thereby repeatedlyrenewing the wavefront-distortion corrected phase pattern. Thephase-modulating includes repeatedly driving the electrically-addressedphase modulated spatial light modulator in accordance with the reneweddistortion corrected phase pattern repeatedly, thereby phase-modulatingthe light. Not only the static wavefront distortion but also the dynamicwavefront distortion can be measured in real time. Accordingly, it ispossible to generate a wavefront-distortion correction phase patternthat corrects different types of wavefront distortion including adynamic wavefront distortion. Phase-modulated light of higher precisioncan therefore be generated.

Preferably, the measuring includes measuring wavefront distortion oflight emitted from the input/output surface of theelectrically-addressed phase modulated spatial light modulator which isnot driven, and the inverting includes inverting the sign of a wavefrontdistortion phase pattern indicating the measured wavefront distortion,thereby generating a first wavefront-distortion correction phasepattern. The adding includes adding the first wavefront-distortioncorrection pattern to the desired phase pattern, thereby generating thedistortion corrected phase pattern.

The first wavefront-distortion correction phase pattern can be generatedonly by inverting the sign of the wavefront-distortion phase patternthat indicates the wavefront-distortion of the light emitted from theinput/output surface of the electrically-addressed phase modulatedspatial light modulator which is not driven. The firstwavefront-distortion correction phase pattern is added to the desiredphase pattern, so that it is possible to correct the wavefrontdistortion of the light induced by the input/output surface of themodulator among the wavefront distortion of the light emitted from theinput/output surface of the electrically-addressed phase modulatedspatial light modulator which is driven in order to generate a desiredphase pattern.

In this case, preferably, the providing a wavefront-distortioncorrection phase pattern further includes: receiving a first wavefrontdistortion correction phase pattern obtained by inverting a sign of awavefront distortion phase pattern indicating the wavefront distortionof the light emerging from the input/output surface of theelectrically-addressed phase modulated spatial light modulator which isnot driven; storing the first wavefront distortion correction phasepattern into the storing means; measuring wavefront distortion of lightinduced by a light source and the first optical component; and invertinga sign of a wavefront distortion phase pattern indicating the measuredwavefront distortion, thereby generating a second wavefront-distortioncorrection phase pattern. The adding includes adding the firstwavefront-distortion correction phase pattern and the secondwavefront-distortion correction phase pattern to the desired phasepattern, thereby the distortion corrected phase pattern. Thephase-modulating includes phase-modulating the light from the lightsource by guiding the light to the electrically-addressed phasemodulated spatial light modulator through the first optical componentand then driving the electrically-addressed phase modulated spatiallight modulator in accordance with the distortion corrected phasepattern.

The second wavefront-distortion correction phase pattern can begenerated merely by inverting the sign of the wavefront-distortion phasepattern indicating the wavefront distortion of light induced by thelight source and the first optical component. Hence, the wavefrontdistortion of light induced by the light source, the first opticalcomponent, and the input/output surface of the electrically-addressedphase modulated spatial light modulator can be corrected merely byadding the second wavefront-distortion correction phase pattern and thefirst wavefront-distortion correction phase pattern to the desired phasepattern.

In this case, the measuring includes repeating measurement of thewavefront distortion of the light in order to repeatedly generate awavefront distortion phase pattern indicating the wavefront distortion.The inverting includes inverting a sign of the wavefront distortionphase pattern, thereby repeatedly generating the wavefront-distortioncorrection phase pattern. The adding includes repeatedly adding thewavefront-distortion correction phase pattern, thereby repeatedlyrenewing the wavefront-distortion corrected phase pattern. Thephase-modulating includes repeatedly driving the electrically-addressedphase modulated spatial light modulator in accordance with the reneweddistortion corrected phase pattern repeatedly, thereby phase-modulatingthe light.

The present invention provides a program executed by a computerincluding: a process of preparing a desired phase pattern; a process ofpreparing a wavefront-distortion correction phase pattern for correctinga wavefront distortion of light; and a process of adding the desiredphase pattern and the wavefront-distortion correction phase pattern,thereby generating a distortion corrected phase pattern. When a sum ofthe desired phase pattern and the wavefront-distortion correction phasepattern has a negative value or a value equal to or more than 2π, aremainder obtained by dividing the sum by 2π is generated as thedistortion corrected phase pattern.

The computer executes the program to only add the wavefront-distortioncorrection phase pattern to the desired phase pattern, thereby obtaininga wavefront-distortion corrected phase pattern. Accordingly, thewavefront-distortion corrected phase pattern can be quickly generated byperforming simple computation.

It is preferable that a program according to the present inventionfurther includes a process of inverting a sign of a wavefront-distortionphase pattern indicating a phase of the wavefront distortion of thelight, thereby generating the wavefront-distortion correction phasepattern. Since the wavefront-distortion correction phase pattern can begenerated merely by inverting the sign of the wavefront-distortion phasepattern, no complex computation is required. The wavefront-distortioncorrection phase pattern can be quickly generated.

The present invention provides a computer-readable recording mediumstoring a program executed by a computer storing: a process of preparinga desired phase pattern; a process of preparing a wavefront-distortioncorrection phase pattern for correcting a wavefront distortion of light;and a process of adding the desired phase pattern to thewavefront-distortion correction phase pattern, thereby generating adistortion corrected phase pattern. When a sum of the desired phasepattern and the wavefront-distortion correction phase pattern has anegative value or a value equal to or more than 2π, a remainder obtainedby dividing the sum by 2π is generated as the distortion corrected phasepattern. When the computer reads the program from the recording mediumof the present invention, the computer can fast and accurately generatea wavefront-distortion correction phase pattern that serves tophase-modulate the light.

Preferably, a recording medium according to the present inventionfurther stores a computer program to perform a process of inverting thesign of a wavefront-distortion phase pattern indicating the phase of thewavefront distortion of the light, thereby generating thewavefront-distortion correction phase pattern. The computer can generatea wavefront-distortion correction phase pattern merely by inverting thesign of the wavefront-distortion phase pattern. Hence, no complexcomputation is required. Accordingly, the wavefront-distortioncorrection phase pattern can be quickly generated.

Alternatively, it is desired that the recording medium according to thepresent invention stores the wavefront-distortion correction phasepattern data. Then, the computer can fast perform the process of addingthe wavefront-distortion correction phase pattern to the desired phasepattern, when the computer reads the program and thewavefront-distortion correction phase pattern data.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the configuration of a laser processapparatus according to a first embodiment of the present invention;

FIG. 2 is a block diagram of a controller provided in the laser processapparatus of FIG. 1;

FIG. 3 is a diagram showing the configuration of the phase modulationmodule incorporated in the laser process apparatus of FIG. 1;

FIG. 4 is a functional block diagram illustrating the controller shownin FIG. 2;

FIG. 5 is a diagram explaining that a CGH pattern H (x, y) and a phasedistortion correction pattern C₁ (x, y) are added to generate awavefront-distortion corrected pattern H′ (x, y) in the first embodimentof the present invention;

FIG. 6 is a one-dimensional diagram showing the phase distribution inthe y-axis direction of a phase distortion pattern Φ₁ (x, y) at givenx-coordinate position, and the phase distribution in the y-axisdirection of a phase distortion correction pattern C₁ (x, y) at a givenx-coordinate position;

FIG. 7(A) is a flowchart explaining the modulation performed in thefirst embodiment of the present invention;

FIG. 7(B) is a flowchart explaining the pattern-adding process carriedout during the modulation of FIG. 7(A);

FIG. 8 is a block diagram explaining that a beam sampler and a wavefrontdetector are arranged in a laser process apparatus in order to generatea distortion correction pattern in the first embodiment of the presentinvention;

FIG. 9(A) is a flowchart explaining a process to generate a distortioncorrection pattern in the first embodiment of the present invention;

FIG. 9(B) is a flowchart explaining the step of calculating adistortion-corrected pattern in the distortion-pattern generatingprocess of FIG. 9(A);

FIG. 10 is a block diagram explaining that a beam sampler and awavefront detector are arranged in a laser process apparatus to generatea distortion correction pattern in the second modification of the firstembodiment of the invention;

FIG. 11 is a block diagram explaining that a measuring device isconnected to a laser process apparatus to generate a distortioncorrection pattern in the third to fifth modifications of the firstembodiment of the present invention;

FIG. 12 is a block diagram illustrating the configuration and functionof a laser process apparatus according to a second embodiment of theinvention;

FIG. 13 is a block diagram illustrating the configuration and functionof a laser process apparatus according to a third embodiment of thepresent invention;

FIG. 14(A) is a view showing the image of a pattern obtained byperforming Fourier transform on the phase-modulated light that has beengenerated by means of a phase-distortion-corrected pattern H′ (x, y)having a corrected wavefront correction in the third embodiment of thepresent invention;

FIG. 14(B) is a view showing the image of a pattern obtained byperforming Fourier transform on the phase-modulated light that has beengenerated by means of a CGH pattern H (x, y) without the wavefront beingcorrected;

FIG. 15 is a flowchart explaining a process to generate a distortioncorrection pattern and modulate light in a fourth embodiment of thepresent invention; and

FIG. 16 is a block diagram illustrating the configuration of awave-shaping device for use in the femtosecond laser according to afifth embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, preferred embodiments of a phase modulating apparatus and aphase modulating method of according to the present invention will bedescribed, with reference to the accompanying drawings.

The identical elements are designated by the same reference symbol inthe figures and will not be repeatedly described.

First Embodiment

A laser process apparatus and a laser process method, both according tothe first embodiment of the invention, will be described with referenceto FIGS. 1 to 9(B).

The present embodiment relates to a laser process apparatus and a laserprocess method, in which a process target T is processed by a laser beamto be formed with any desired pattern.

As shown in FIG. 1, the laser process apparatus 1 according to the firstembodiment includes a reading light source 10, a spatial filter 20, acollimate lens 30, a phase modulation module 40, a Fourier lens 50, anda controller 60.

The reading light source 10 is constituted by an He—Ne laser to generatecoherent reading light. The reading light emitted from the reading lightsource 10 has an almost uniform phase distribution in the cross section.The reading light is a linear polarization having a polarization planeparallel to the plane of FIG. 1.

The spatial filter 20 removes excessive diffracted waves and excessivereflected waves from the reading light. The spatial filter 20 alsoremoves diffracted and scattered waves generated due to flaws and dustfrom the reading light.

The collimate lens 30 collimates the reading light emerging from thespatial filter 20 to generate parallel reading light.

The phase modulation module 40 is an electrically-addressed phasemodulated spatial light modulator to perform phase modulation on thereading light coming from the collimate lens 30.

The Fourier lens 50 performs spatial Fourier transform on the readinglight that has been phase-modulated by the phase modulation module 40.The process target T is positioned on the Fourier plane of the Fourierlens 50. Hence, the reading light is first guided from the light source10 to the phase modulation module 40 through the spatial filter 20 andthe collimate lens 30. The reading light is then guided from the phasemodulation module 40 to the process target T through the Fourier lens50.

The controller 60 includes a personal computer to control the phasemodulation module 40.

As shown in FIG. 2, the controller 60 includes a hard disk drive 61, aCPU 62, a ROM 64, a RAM 63, a reading device 65 for reading data from arecording medium, an input/output (I/O) interface 66, and a networkcontrol unit (NCU) 67, which are connected to each other through a bus.

The hard disk drive 61 stores a program for generating distortioncorrection patterns, a program for generating distortion correctedpatterns, and a program for driving the module in advance. Theseprograms will be described later.

The CPU 62 controls all operations of the controller 60 to executesvarious programs, such as the program for generating distortioncorrection patterns, the program for generating distortion correctedpatterns, and the program for driving the module.

The RAM 63 is provided to store the data that the CPU 62 generates whenthe CPU 62 executes any program.

The ROM 64 stores various programs and data. The ROM 64 may store theprogram for generating distortion correction patterns, the program forgenerating distortion corrected patterns, and the program for drivingthe module.

The reading device 65 is configured to read programs and data from arecording medium such as a flexible disk, a CD-ROM and a DVD to storethe programs and data in the hard disk drive 61. For example, theprogram for generating distortion correction patterns and the programfor generating distortion corrected patterns are stored in a recordingmedium such as a flexible disk, a CD-ROM or a DVD. In this case, thereading device 65 reads the programs from the recording medium to storethe programs in the hard disk drive 61.

The phase modulation module 40 is connected to the input/output (I/O)interface 66. A wavefront detector 210 (FIG. 8), which will be describedlater, can be connected to the input/output (I/O) interface 66. Further,an input device (not shown) such as a keyboard and a mouse, and anoutput device (not shown) such as a display and a printer are connectedto the input/output (I/O) interface 66.

A network 68 such as the Internet is connected to the network controlunit. Accordingly, it is possible to down-load the program forgenerating distortion correction patterns and the program for generatingdistortion corrected patterns from the network 68 such as the Internetand store these programs in the hard disk drive 61.

The phase modulation module 40 will be described, with reference to FIG.3.

As shown in FIG. 3, the phase modulation module 40 includes a writinglight source 110, a collimate lens 120, a liquid-crystal display(referred to as “LCD” hereinafter) 130, a relay lens 140, and aparallel-aligned nematic-liquid-crystal spatial light modulator(referred to as “PAL-SLM” hereinafter) 150.

The writing light source 110 is designed to generate writing light thathas a uniform intensity distribution in the cross section. For example,the writing light source 110 is constituted by a laser diode (LD).

The collimate lens 120 collimates the writing light emerging from thewriting light source 110 to generate parallel light.

The LCD 130 is a transmission type of electrically-addressed intensitymodulated spatial light modulator. When electrically driven with adesired pattern in an addressing mode, the LCD 130 intensity-modulatesthe writing light emerging from the collimate lens 120 to generateintensity-modulated light that has intensity distribution of a desiredpattern in the cross section.

The LCD 130 is composed of a light-receiving layer 130 a, alight-transmitting layer 130 b, a pixel assembly layer 130 c, a twistnematic liquid-crystal layer 130 d, and a facing electrode layer 130 e.The pixel assembly layer 130 c is interposed between the light-receivinglayer 130 a and the light-transmitting layer 130 b. The light-receivinglayer 130 a is formed of a transparent glass substrate and a polarizingplate on the outer surface of the glass plate. Similarly, thelight-transmitting layer 130 b is formed of a transparent glasssubstrate and a polarizing plate on the outer surface of the glasssubstrate. The pixel assembly layer 130 c has a plurality of transparentpixel electrodes. The transparent pixel electrodes are arranged at aprescribed pitch P in a two-dimensional matrix form in a plane that isperpendicular to the optical axis of the collimate lens 120 (The planeis an xy-plane perpendicular to the plane of FIG. 3, where the x axis isperpendicular to the plane of FIG. 3 and the y axis is parallel to theplane of FIG. 3). Note that the position of each transparent pixelelectrode is defined by a corresponding coordinate (x, y) in thexy-plane.

In the LCD 130 configured above, the light-receiving layer 130 a isarranged to face the collimate lens 120 and the light-transmitting layer130 b is arranged to face the relay lens 140. The pixel assembly layer130 c is connected to the controller 60. When the transparent pixelelectrodes of the pixel assembly layer 130 c are electrically-drivenwith a desired pattern in an addressing mode by a control unit 60 g(described later) of the controller 60, the liquid-crystal molecules inthe twist nematic liquid-crystal layer 130 d change their orientation inaccordance with the desired pattern.

When the writing light emerging from the collimate lens 120 impinges onthe twist nematic liquid-crystal layer 130 d through the polarizingplate of the light-receiving layer 130 a, the polarization of the lightis changed. The writing light is generated as intensity-modulated lightwhen the writing light passes the polarizing plate of thelight-transmitting layer 130 b. Thus, the LCD 130 can outputintensity-modulated light that has intensity distribution of a desiredpattern in the cross section.

The relay lens 140 transmits the intensity-modulated light emerging fromthe LCD 130 to the PAL-SLM 150. The relay lens 140 has a numericalaperture NAL on the side of the LCD 130. The numerical aperture NAL hasa value that satisfies the relationship of ½P<NA_(L)/λ<1/P, where P isthe pixel pitch of the LDC 130 and λ is the wavelength of the writinglight of the writing light source 110. Then, the relay lens 140 caneliminate the signal component of spatial frequency 1/P, which resultsfrom the pixel assembly layer 130 c of the LDC 130, and can transmit theintensity pattern displayed on the LCD 130 to the PAL-SLM 150 with highaccuracy.

The PAL-SLM 150 is a reflection type of optically-addressed phasemodulated spatial light modulator. The PAL-SLM 150 is opticallyaddressed by the intensity-modulated light transmitted via the relaylens 140, thereby phase-modulating the reading light that has passedthrough the collimate lens 30. Thus, the PAL-SLM 150 generates thephase-modulated light that has phase distribution of a desired patternin the cross section. The PAL-SLM 150 is composed of a writing-sidetransparent substrate 150 a, a reading-side transparent substrate 150 b,a transparent electrode 150 c, a photoconductive layer 150 d, a mirrorlayer 150 e, a liquid-crystal layer 150 f, and another transparentelectrode 150 g. The transparent electrode 150 c is interposed betweenthe writing-side transparent substrate 150 a and reading-sidetransparent substrate 150 b. The reading-side transparent substrate 150b defines an incidence and emission plane for the reading light. Thissubstrate 150 b is made of transparent material such as glass.

The transparent electrodes 150 c and 150 g are electrically connected toan AC power supply (not shown). The photoconductive layer 150 d is madeof amorphous silicon. The liquid-crystal layer 150 f includes nematicliquid-crystals, the molecules of which are horizontally oriented. Theliquid-crystal molecules rotate in a specific plane in accordance withthe voltage applied to the layer 150 f, to change the refractive indexof the liquid-crystal layer 150 f.

The PAL-SLM 150 thus configured has the writing-side transparentsubstrate 150 a facing the relay lens 140, and the reading-sidetransparent substrate 150 b facing the collimate lens 30 and Fourierlens 50. In addition, the PAL-SLM 150 is positioned in order that thereading light emerging from the collimate lens 30 impinges on thereading-side transparent substrate 150 b obliquely. That is, the readinglight impinges on the reading-side transparent substrate 150 b obliquelyat a predetermined incidence angle θ with respect to an optical axis Iof the incidence light. After the reading light is reflected by themirror layer 150 e, the reading light emerges from the reading-sidetransparent substrate 150 b along optical axis O of reflection inclinedat reflection angle θ that is identical to the incidence angle to reachthe Fourier lens 50. Note that the reading light source 10 is orientedso that the reading light, or lineally polarized light P, impinges onthe PAL-SLM 150 as a p-polarized beam. In the PAL-SLM 150, theliquid-crystal molecules in the liquid-crystal layer 150 f are orientedalmost parallel to the polarization plane of the reading light.Accordingly, a predetermined plane on which the liquid crystal moleculesrotate in accordance with the voltage applied to the liquid-crystallayer 150 f is almost parallel to the normal plane of the reading light.(Note that the normal plane is the plane of FIG. 3, containing theoptical axis I of incidence of the reading light, the optical axis O ofreflection thereof, and the normal to the mirror layer 150 e.)

When the intensity-modulated light emitting from the LCD 130 impingesand focuses on the photoconductive layer 150 d through the relay lens140, the crystal structure of the amorphous silicon of thephotoconductive layer 150 d changes, thereby changing a voltage appliedacross the liquid-crystal molecules. Accordingly, the photoconductivelayer 150 d exhibits Electrically Controlled Birefringence (ECB) effectin which the liquid-crystal molecules are rotated to change the index ofbirefringence of the liquid-crystal layer 150 f. Hence, the readinglight which has passed through the collimate lens 30 is phase-modulatedwhen propagating in the liquid-crystal layer 150 f. The reading light isreflected at the mirror layer 150 e, propagates in the liquid-crystallayer 150 f again, and exits from the PAL-SLM as the phase-modulatedlight. The phase-modulated light has phase distribution with a wavefrontdistortion, which corresponds to the intensity distribution of theintensity-modulated light emerging from the LCD 130. The phase-modulatedlight emitted from the PAL-SLM 150 undergoes spatial Fourier transformin the Fourier lens 50 to be focused on the process target T.

The structures of the PAL-SLM 150 and phase modulation module 40 aredetailed in PCT publication WO00/34823, for example.

As shown in the functional block diagram of FIG. 4, the controller 60includes a pattern memory unit 60 a, a distortion pattern memory unit 60b, a distortion-correction pattern generating unit 60 c, adistortion-correction pattern memory unit 60 d, an adder unit 60 e, adistortion-corrected pattern memory unit 60 f, a control unit 60 g, adistortion pattern input unit 60 h, a pattern input unit 60 i, and apattern generating unit 60 j. The pattern memory unit 60 a, thedistortion pattern memory unit 60 b, the distortion-correction patternmemory unit 60 d, and the distortion-corrected pattern memory unit 60 fare constituted in the hard disk drive 61.

The distortion-correction pattern generating unit 60 c is controlled bythe CPU 62 to executes the program for generating distortion correctionpatterns to generate distortion correction patterns. The adder unit 60 eis controlled by the CPU 62 to execute the program for generatingdistortion corrected patterns, thereby adding patterns as will beexplained later. The control unit 60 g is controlled by the CPU 62 toexecute the program for driving the module, thus driving the phasemodulation module 40. The distortion pattern input unit 60 h includesthe input/output (I/O) interface 66. The pattern input unit 60 iincludes either one of the reading device 65 and the NCU 67. The patterngenerating unit 60 j is controlled by the CPU 62 to execute animage-generating program to generate desired phase patterns.

The pattern memory unit 60 a stores data H (x, y) that represents adesired phase pattern by which the process target T should be processed.In the present embodiment, the desired phase pattern data represents acomputer-generated hologram pattern (hereinafter referred to as “CGHpattern”). The CGH pattern data H (x, y) indicates the phase value(i.e., amount of phase modulation) by which light should bephase-modulated at each position (x, y) of a transparent pixel electrodein the pixel assembly layer 130 c of the LCD 130 of the phase modulationmodule 40.

More specifically, the CGH pattern data H (x, y) includes the phasevalue for every pixel (x, y) as is illustrated in FIG. 5. For example,the CGH pattern data H (x, y) value for the pixel at position (0, 0) onthe upper-left corner is 2.5π, and the CGH pattern data H (x, y) valuefor the pixel immediately right to this pixel is 3.4π. In FIG. 5, apixel with phase value 0 has black color, a pixel with phase value 2πhas while color, and a pixel with a phase value ranging from 0 to 2π hasgray color. In FIG. 5, any pixel having a phase value equal to orgreater than 2π or a negative phase value is replaced by one having aphase value ranging from 0 to 2π, which is the remainder obtained bydividing the phase value by 2π.

Note that the CGH pattern data H (x, y) is data that the CPU 62 (patterngenerating unit 60 j) has generated as it executes a program for images.Alternatively, the CGH pattern data (x, y) can be entered via thepattern input unit 60 i from outside. In this case, the CGH pattern data(x, y) has been stored in a recording medium such as a flexible disk, aCD-ROM or a DVD or has been uploaded to the network 68. The readingdevice 65 or the NCU 67 (i.e., pattern input unit 60 i) receives the CGHpattern data H (x, y) from the recording medium or the network 68 tostore the data into the pattern memory unit 60 a.

The distortion pattern memory unit 60 b is provided to store the datathat represents the phase distortion pattern Φ₁ (x, y) of the readinglight that has passed through the collimate lens 30. The reading lightemitting from the reading light source 10 has static phase distortion atthe wavefront, which is caused because of the structure of the readinglight source 10. Further, static phase distortion occurs at thewavefront of the reading light due to the aberration of the spatialfilter 20 and collimate lens 30 because the reading light passes throughthe spatial filter 20 and collimate lens 30. Thus, the reading lightcoming from the collimate lens 30 has wavefront distortion as a curvingline shown in FIG. 4 because of the optical system including the readinglight source 10, the spatial filter 20, and the collimate lens 30. Thedistortion pattern memory unit 60 b stores the phase distortion patternΦ₁(x, y) that indicates the wavefront distortion. Note that “(x, y)”represents a point in a plane that is perpendicular to the optical axisof the reading light. This point (x, y) corresponds to the position ofeach transparent pixel electrode provided in the pixel assembly layer130 c of the LCD 130. That is, the phase distortion pattern Φ₁ (x, y)indicates the phase value for every position (x, y) and defines thewavefront distortion of the reading light, namely a distribution of theadvanced and delayed parts of the wavefront (i.e., the curving line inFIG. 4).

The data of the phase distortion pattern Φ₁ (x, y) is entered via theinput/output (I/O) interface 66 (more correctly, the distortion patterninput unit 60 h). In other words, the input/output (I/O) interface 66(distortion pattern input unit 60 h) receives the data about the phasedistortion pattern Φ₁ (x, y) from the wavefront detector 210, which willbe described later, to store the data into the distortion pattern memoryunit 60 b.

The distortion-correction pattern generating unit 60 c generates data ofa phase distortion correction pattern C₁ (x, y) for eliminating thewavefront-distortion pattern, based on the data representing thewavefront distortion pattern Φ₁ (x, y) stored in the distortion patternmemory unit 60 b. More precisely, the distortion-correction patterngenerating unit 60 c calculates the pattern −Φ₁ (x, y) that is inverseto the pattern Φ₁ (x, y) to set the phase distortion pattern −Φ₁ (x, y)as a phase distortion correction pattern C₁ (x, y). Accordingly, thephase distortion correction pattern C₁ (x, y) indicates a phase valuefor every position (x, y).

As described above, the phase distortion correction pattern C₁ (x, y) isa pattern for delaying the advanced parts of the wavefront Φ₁ (x, y) andadvancing the delayed parts thereof, which are illustrated as a curvingline in FIG. 4. Assume that the phase distortion pattern Φ₁ (x, y) has adistribution along the y-axis direction distorted at a givenx-coordinate position in, as shown in FIG. 6. Then, the phase distortioncorrection pattern C₁ (x, y) is generated in order that a plane wave asillustrated in FIG. 6 may be generated by adding the phase distortionpattern Φ₁ (x, y) to the phase distortion correction pattern C₁ (x, y).As shown in FIG. 5, the phase distortion correction pattern C₁ (x, y)has a value of 3.5π at a position (0, 0) on the upper-left corner, andhas another value of 2.1π at the next right-hand position (1, 0).

The distortion-correction pattern memory unit 60 d is designed to storethe data of the phase distortion correction pattern C₁ (x, y) generatedby the distortion-correction pattern generating unit 60 c.

The adder unit 60 e adds the CGH pattern data H (x, y) stored in thepattern memory unit 60 a to the phase distortion correction pattern dataC₁ (x, y) stored in the distortion-correction pattern memory unit 60 dto generate data of a phase-distortion corrected pattern H′ (x, y). Thatis, the adder unit 60 e performs operation of H′ (x, y)=H (x, y)+C₁ (x,y).

To be more specific, the adder unit 60 e adds the CGH pattern data H (x,y) and the phase-distortion correction pattern data C₁ (x, y) for everypixel position (x, y) to generate a phase-distortion corrected patternH′ (x, y) as illustrated in FIG. 5. In the phase distortion correctedpattern H′ (x, y) thus generated, the position (0, 0), or the upper-leftcorner, has a phase value of 6π (=2.5π+3.5π), and the position (1, 0)has a phase value of 5.5π(=3.4π+2.1π).

Since the reading light consists of continuous waves, the output of theadding unit 60 e is not changed even if the wavefront is displaced byone-wave length, or 2π-phase. Thus, the adder unit 60 e performs aconversion process (hereinafter referred to as “phase turn-up process”)when the phase-distortion corrected pattern data H′ (x, y) has anegative phase value or a phase value equal to or greater than 2π forevery pixel (x, y). In the phase turn-up process, the phase value foreach pixel is replaced with the remainder obtained by dividing the phasevalue by 2π. For example, the phase value H′ (0, 0)=6π for the pixelposition (0, 0) is converted to H′ (0, 0)=0. The phase value H′ (1,0)=5.5π for the pixel position (1, 0) is converted to H′ (1, 0)=1.5π. Tofind the remainder of dividing a negative phase value by 2π, theabsolute value of the negative phase is first obtained, and a minimumpositive value is then obtained which yields an integral multiple of 2πwhen added to the absolute value. For example, if the phase value H′ (2,0) for the pixel position (2, 0) is −0.3π, the phase value H′ (2, 0) isconverted to 1.7π. In the present embodiment, the adder unit 60 ecarries out the phase turn-up process. Therefore, even if the PAL-SLM150 cannot perform phase modulation at a phase value of 2π or more, thePAL-SLM 150 can perform essentially the same phase modulation by usingthe remainder of dividing the phase value by 2π.

The distortion-corrected pattern memory unit 60 f is used to store thedistortion-corrected pattern data H′ (x, y) generated by the adder unit60 e.

The control unit 60 g generates a drive signal based on thedistortion-corrected pattern data H′ (x, y) stored in thedistortion-corrected pattern memory unit 60 f to drive the LCD 130incorporated in the module 40.

The modulation process by the laser process apparatus 1 of theabove-described configuration will be explained with reference to FIG.7(A).

The adder unit 60 e starts adding patterns, when a user instructs thelaser process apparatus 1 to operate through the input device of thecontroller 60 (S1).

The pattern-adding process (S1) will be described, with reference toFIG. 7(B).

In the pattern-adding process, the CPU 62 first reads a desired CGHpattern data H (x, y) from the pattern memory unit 60 a (step S2).

The CPU 62 then reads a phase distortion correction pattern data C₁ (x,y) from the distortion-correction pattern memory unit 60 d (step S3).

Next, the CPU 62 adds the CGH pattern data H (x, y) and the phasedistortion correction pattern data C₁ (x, y), thereby generating phasedistortion corrected pattern data H′ (x, y) (=H (x, y)+C₁ (x, y)) (stepS4). If the value of the phase distortion corrected pattern data H′ (x,y) for every pixel (x, y) has a negative value or a value equal to orgreater than 2π, the adder unit 60 e performs the phase turn-up process,in which the value is replaced with the remainder obtained by dividingthe phase value by 2π.

As described above, phase distortion corrected pattern data H′ (x, y) isobtained. This data is stored into the distortion-corrected patternmemory unit 60 f (step S5).

Thus, the pattern-adding process (S1) is completed.

Thereafter, the CPU 62 carries out a driving process to drive the phasemodulation module 40 in step S7. More specifically, the CPU 62 generatesa drive signal based on the phase distortion corrected pattern data H′(x, y) to drive every transparent pixel electrode at a pixel position(x, y) in the pixel assembly layer 130 c of the LCD 130. At the sametime, the writing light source 110 and the reading light source 10 areturned on. The LCD 130 generates intensity-modulated light having theintensity distribution of the phase distortion corrected pattern H′ (x,y). The intensity-modulated light is transmitted through the relay lens140 to the photoconductive layer 150 d of the PAL-SLM 150. The PAL-SLM150 is optically addressed by the intensity-modulated light that has theintensity distribution of the phase distortion corrected pattern H′ (x,y) in cross section. The reading light having the wavefront distortionof the phase distortion pattern Φ₁ (x, y) in cross section passesthrough the collimate lens 30 to the PAL-SLM 150. The PAL-SLM 150phase-modulates the reading light with the phase distortion correctedpattern H′ (x, y) to generate phase-modulated light that has theoriginal wavefront of the CGH pattern H (x, y).

That is to say, the PAL-SLM 150 phase-modulates the reading light havingthe wavefront distortion of the phase distortion pattern Φ₁ (x, y) withthe phase distortion corrected pattern H′ (x, y) to carry out additionof phase distributions, which is expressed by the following equation(1): $\begin{matrix}{{{\Phi_{1}\left( {x,y} \right)} + {H^{\prime}\left( {x,y} \right)}} = {{{\Phi_{1}\left( {x,y} \right)} + \left\{ {{C_{1}\left( {x,y} \right)} + {H\left( {x,y} \right)}} \right\}} = {{{\Phi_{1}\left( {x,y} \right)} + \left\{ {{- {\Phi_{1}\left( {x,y} \right)}} + {H\left( {x,y} \right)}} \right\}} = {H\left( {x,y} \right)}}}} & (1)\end{matrix}$

Thus, the PAL-SLM 150 generates the reading light that has the phasedistribution of a desired CGH pattern H (x, y). This reading lightpasses through the Fourier lens 50 to form a desired patterncorresponding to the CGH pattern H (x, y) on the process target H.

Note that the program for generating the distortion corrected patternsis constituted by a program that performs the pattern-adding process(S1). It should also be noted that the program for driving the module isconstituted by a program that performs step S7.

As described above, in the present embodiment, the phase distortioncorrection pattern C₁ (x, y) is stored beforehand in thedistortion-correction pattern memory unit 60 d. Accordingly, it ispossible to obtain the phase distortion corrected pattern H′ (x, y) justby reading the pattern C₁ (x, y) from the memory unit 60 d and addingthe pattern C₁(x, y) to the desired phase pattern H (x, y). Therefore,the phase distortion corrected pattern H′ (x, y) can be acquired withina short time. It is therefore possible to perform a real-time controlfor the phase distortion corrected pattern H′ (x, y).

Even if the reading light source 10, the spatial filter 20, and thecollimate lens 30 are not high precision optical members, the phasemodulation module 40 can efficiently generates light phase-modulatedwith the desired phase pattern H (x, y) when the phase modulation module40 is driven by the phase distortion corrected pattern H′ (x, y).Accordingly, expensive optical members are not required. In addition,the structure of the laser process apparatus 1 can be made simple, sothat the laser process apparatus 1 is manufactured at lower cost.

In this embodiment, the laser process apparatus 1 performs adistortion-correction pattern forming process before starting processingthe process target. Namely, the wavefront distortion of the readinglight emerging from the collimate lens 30 is measured, so that phasedistortion pattern data Φ₁ (x, y) is generated. And then phasedistortion correction pattern data C₁ (x, y)=−Φ₁ (x, y) is generated tobe stored in the distortion-correction pattern memory unit 60 d.

The distortion-correction pattern forming process will be explained,with reference to FIG. 8 to FIG. 9(B).

To generate the distortion-correction pattern, a user arranges a beamsampler 200 and a wavefront detector 210 in the laser process apparatus1, as illustrated in FIG. 8. In FIG. 8, only the distortion patterninput unit 60 h and the control unit 60 g are shown to facilitateunderstanding, and other members 60 a to 60 f, 60 i and 60 j of thecontroller 60 are not illustrated.

The beam sampler 200 is configured to reflect a part of the incidentlight, and allow the rest of the incident light to pass therethrough. Inthe present embodiment, the beam sampler 200 is located downstream ofthe collimate lens 30. The beam sampler 200 reflects a part of thereading light that has passed through the collimate lens 30, and allowsthe remaining part of the reading light to pass therethrough to thephase modulation module 40.

The wavefront detector 210 measures a wavefront of the incident lightthereon. For example, the detector 210 consists of a well-knownShack-Hartmann sensor. The Shack-Hartmann sensor is composed of a lensarray, a two-dimensional detector, and a signal-processing unit, whichare not shown. The lens array collects light. The two-dimensionaldetector converts a light spot focused on the lens array into an imagesignal. The signal-processing unit processes the image signal togenerate data that represents a wavefront pattern of the light. Thewavefront detector 210 configured above is located at a position toreceive the light reflected by the beam sampler 200. The detector 210detects the wavefront of the incident light to generate the phasedistortion pattern data representing the distortion of the wavefront. Asignal-processing unit of the wavefront detector 210 is connected to theinput/output (I/O) interface 66 (the distortion pattern input unit 60 h)of the controller 60, so that the phase distortion pattern datagenerated by the detector 210 can be entered to the controller 60. Thewavefront detector 210 may be constituted by an interferometer.

After the user installs the wavefront detector 210 in the laser processapparatus 1, a measuring process is started as shown in FIG. 9(A) (stepS10). That is, the user starts driving the reading light source 10. Thebeam sampler 200 reflects a part of the reading light emerging from thecollimate lens 30 to guide the reflected light to the wavefront detector210. The wavefront detector 210 measures the wavefront of the incidentreading light to generate the phase distortion pattern data Φ₁ (x, y)that indicates the wavefront distortion of the light. The phasedistortion pattern data Φ₁ (x, y) is then stored via the distortionpattern input unit 60 h into the distortion pattern memory unit 60 b.When the wavefront detector 210 finishes measuring the wavefront of thereading light, the reading light source 10 is turned off.

Next, the controller 60 starts a pattern-calculating process (step S20).

The pattern-calculating process will be explained with reference to FIG.9(B).

In the pattern-calculating process, the distortion-correction patterngenerating unit 60 c reads the phase distortion pattern data Φ₁ (x, y)from the distortion pattern memory unit 60 b. The unit 60 c then invertsthe sign of the phase distortion pattern data Φ₁ (x, y), therebygenerating phase distortion correction pattern data C₁ (x, y) (stepS26). That is to say, the distortion-correction pattern generating unit60 c performs the operation of C₁ (x, y)=−Φ₁ (x, y) to obtain a phasedistortion correction pattern C₁ (x, y).

The phase-distortion correction pattern data C₁ (x, y) is stored in thedistortion-correction pattern memory unit 60 d (step S28). Thus, thepattern-calculating process (step S20 shown in FIG. 9(A)) is finished,and a distortion-correction pattern generating process is also over. Theuser removes the beam sampler 200 and wavefront detector 210 from thelaser process apparatus 1 to return the system to the state shown inFIG. 1.

As described above, in this embodiment, the laser process apparatus 1first measures a phase distortion pattern data Φ₁ (x, y) and thengenerates a phase distortion correction pattern C₁ (x, y), therebystoring the resultant pattern C₁ (x, y) into the distortion-correctionpattern memory unit 60 d.

It should be noted that the program for generating adistortion-correction pattern includes a program for executing thepattern-calculating process S20 (i.e., step S20 shown in FIG. 9(B)).

(First Modification)

Hereinafter, a first modification of the present embodiment will bedescribed.

As described above, the laser process apparatus 1 has the structureillustrated in FIG. 1. The beam sampler 200 and the wavefront detector210 are incorporated in the laser process apparatus 1 as shown in FIG.8, only when the distortion-correction pattern forming process (FIG.9(A), FIG. 9(B)) is executed. Alternatively, the laser process apparatus1 may have the structure of FIG. 8. That is, the beam sampler 200 andthe wavefront detector 210 may be installed in the apparatus 1 as isillustrated in FIG. 8. In this case, the laser process apparatus 1having the structure shown in FIG. 8 performs the distortion-correctionpattern forming process (FIG. 9(A), FIG. 9(B)) and then performs thephase modulation (FIG. 7(A), FIG. 7(B)). The beam sampler 200 passesthrough and guides most part of the reading light to the phasemodulation module 40, so that the phase modulation module 40 can exertthe phase modulation on most of the reading light emerging from thereading light source 10. Therefore, the processing of the target is nothindered by the beam sampler 200 in the optical path of the readinglight.

(Second Modification)

As shown by the curving dashed line of FIG. 1, the wavefront of thereading light may have static phase distortion due to the lowsurface-precision of the reading-side transparent substrate 150 bprovided in the PAL-SLM 150. More precisely, the reading light isdistorted when passing through the reading-side transparent substrate150 b of the PAL-SLM 150. In view of this, the static wavefrontdistortion due to the reading light source 10, the spatial filter 20,the collimate lens 30, and the PAL-SLM 150 may be measured in advanceand eliminated.

In the present modification, in the process of generating awavefront-distortion correction pattern (FIG. 9(A)), the beam sampler200 is placed downstream of the phase modulation module 40 to reflect apart of the reading light emerging from the PAL-SLM 150 to the wavefrontdetector 210, as illustrated in FIG. 10. In this condition, themeasuring process (S110) shown in FIG. 9(A) is carried out. In FIG. 10,only the distortion pattern input unit 60 h and the control unit 60 gare shown as in FIG. 8. And the other members 60 a to 60 f, 60 i and 60j of the controller 60 are not illustrated.

While the wavefront detector 210 detects the wavefront distortion inS10, the control unit 60 g keeps the phase modulation module 40 off.Namely, the control unit 60 g does not supply a drive signal to the LCD130, turns off the writing light source 110, and does not apply avoltage from the AC power supply (not shown) to the PAL-SLM 150. Thisconditions inhibit the liquid-crystal layer 150 f of the PAL-SLM 150from phase-modulating the reading light. The wavefront detector 210 cantherefore detect wavefront distortion induced due to the reading lightsource 10, the spatial filter 20, the collimate lens 30, and thereading-side transparent substrate 150 b of PAL-SLM 150 (hereinafterreferred to as “Φ₂ (x, y)”). The wavefront detector 210 stores thedetected phase distortion pattern Φ₂ (x, y) in the distortion patternmemory unit 60 b through the distortion pattern input unit 60 h.

It is not preferable to drive the phase modulation module 40 during themeasuring process S10 (FIG. 9(A)). Suppose that the phase modulationmodule 40 is turned on. That is, if a drive signal was supplied to theLCD 130, thus turning on the writing light source 110, and an AC voltagewas applied to the PAL-SLM 150, the LCD 130 would generateintensity-modulated light that represents a kind of pattern, so that thePAL-SLM 150 processes the wavefront of the reading light in accordancewith the intensity-modulated light to generate the phase patterncorresponding to the intensity-modulated light (wavefront distortion).In this case, the wavefront detector 210 detects the wavefrontdistortion due to the optical members 10 to 30 and 150 and the wavefrontdistortion due to the pattern appearing on the LCD 130 together whichare superimposed to each other. In other words, the detector 210 cannotdetect only the wavefront distortion due to the members 10 to 30 and150, independently of the wavefront distortion due to the pattern.

In the pattern-calculating process of FIG. 9(B), thedistortion-correction pattern generating unit 60 c reads the phasedistortion pattern data Φ₂ (x, y) from the distortion pattern memoryunit 60 b in step S26 to calculate an inverse pattern C₂ (x, y) of thepattern data Φ₂(x, Y) (=−Φ₂ (x, y)). In step S28, the inverse pattern C₂(x, y) is stored in the distortion-correction pattern memory unit 60 das a phase-distortion correction pattern. Thus, after thepattern-calculating process (S20) is finished, the beam sampler 200 andwavefront detector 210 are removed from the laser process apparatus 1.The laser process apparatus 1 then returns to the state shown in FIG. 1.

In the phase modulation (FIG. 7(A), FIG. 7(B)), the adder unit 60 e addsthe phase-distortion correction pattern C₂ (x, y) and a desired CGHpattern H (x, y) to generate a phase distortion corrected pattern H′ (x,y) (S1). A drive signal for the LCD 130 is generated based on theresultant phase distortion corrected pattern H′ (x, y) to drive thephase modulation module 40 (S7).

In this modification, the wavefront detector 210 detects the phasedistortion pattern Φ₂ (x, y) due to the reading light source 10, thespatial filter 20, the collimate lens 30, and the reading-side substrate150 b of PAL-SLM 150. For eliminating the pattern Φ₂ (x, y), a phasedistortion correction pattern C₂ (x, y) is generated to add to a desiredCGH pattern H (x, y), thereby obtaining a phase distortion correctedpattern H′. The phase modulation module 40 is driven with the phasedistortion corrected pattern H′ (x, y), so that phase-modulated lightthat has the phase distribution of the desired CGH pattern H (x, y) incross section can be generated without any distortion. As thephase-modulated light passes through the Fourier lens 50, a desiredpattern corresponding to the CGH pattern H (x, y) is reliably formed onthe process target T.

As described above, in the present modification, the LCD 130 iscontrolled with the phase distortion corrected pattern H′ (x, y), evenif the reading-side transparent substrate 150 b of PAL-SLM 150 hasdistortion. Therefore, it is possible to generate light that isphase-modulated with a desired pattern H (x, y) at high precision.Accordingly, the laser process apparatus 1 can be manufactured at lowercost.

In this modification, the beam sampler 200 and wavefront detector 210may be installed in the apparatus 1 as is shown in FIG. 10, similarly tothe first modification. In this case, after the laser process apparatus1 performs the process of generating a distortion-correction pattern(FIG. 9(A), FIG. 9(B)) by means of the configuration of FIG. 10, themodulation process (FIG. 7(A), FIG. 7(B)) is performed. In themodulation, the beam sampler 200 passes through and guides most of theincident reading light to the Fourier lens 50. The Fourier lens 50performs Fourier transform on the phase-modulated light, so that thelight is used to process the target.

(Third Modification)

Only the wavefront distortion resulting from the reading-sidetransparent substrate 150 b of PAL-SLM 150 may be measured before thephase modulation module 40 is disposed in the laser process apparatus 1.In other words, measuring equipment 70 having a wavefront detector 220is provided to be connected to the distortion pattern input unit 60 h(input/output (I/O) interface 66) of the controller 60. The wavefrontdetector 220 has the same structure as that of the wavefront detector210 and operates in the same way as the wavefront detector 210. In FIG.11, only the distortion pattern input unit 60 h and the control unit 60g are shown similarly to FIGS. 8 and 10, and other members 60 a to 60 f,60 i and 60 j of the controller 60 are not illustrated.

In this case, the process of generating a distortion-correction pattern(FIG. 9(A), FIG. 9(B)) is carried out as will be described below.

First, a user inserts the phase modulation module 40 as sample into themeasuring equipment 70. The measuring process (S10) is started. That is,the phase modulation module 40 is turned off, and the reading lightemerging from a predetermined reading light source and having correctedwavefront distortion is irradiated to the reading-side transparentsubstrate 150 b of PAL-SLM 150. The wavefront detector 220 measures thewavefront distortion of the reading light emitted from the reading-sidetransparent substrate 150 b. Assume that the phase distortion pattern ofthe reading-side transparent substrate 150 b of PAL-SLM 150 isdetermined to be a phase distortion pattern Φ₁₅₀ (x, y). Then, thewavefront detector 220 transfers the pattern data Φ₁₅₀ (x, y) to thedistortion pattern memory unit 60 b through the distortion pattern inputunit 60 h.

Instead of setting the whole of the phase modulation module 40 in themeasuring equipment 70, only the PAL-SLM 150 may be arranged in themeasuring equipment 70 before being mounted into the phase modulationmodule 40. In this case, the PAL-SLM 150 is maintained off. Morecorrectly, no AC voltage is applied to the PAL-SLM 150. No writing lightirradiates the PAL-SLM 150. Reading light emerging from the readinglight source and having corrected wavefront distortion irradiates thereading-side transparent substrate 150 b of PAL-SLM 150. At this time,the wavefront detector 220 measures the wavefront distortion Φ₁₅₀ (x, y)of the reading light emitted from the reading-side transparent substrate150 b.

Next, the pattern-calculating process (S20) is carried out. As shown inFIG. 9(B), the distortion-correction pattern generating unit 60 c readsthe data Φ₁₅₀ (x, y) from the distortion pattern memory unit 60 b instep S26. The unit 60 c then calculates a phase distortion correctionpattern C₁₅₀ (x, y) for correcting the phase distortion pattern Φ₁₅₀ (x,y) by using the following equation:C ₁₅₀(x, y)=−Φ₁₅₀(x, y)  (2)

The resultant phase-distortion correction pattern C₁₅₀ (x, y) is storedinto the distortion-correction pattern memory unit 60 d (S28).

In the modulation process (FIG. 7(A), FIG. 7(B)), the adder unit 60 ereads the phase-distortion correction pattern C₁₅₀ (x, y) from thedistortion-correction pattern memory unit 60 d (S3). The unit 60 e addsthis phase-distortion correction pattern C₁₅₀ (x, y) to a desired CGHpattern H (x, y), thus generating a phase distortion corrected patternH′ (x, y) (S4). In other words, the adder unit 60 e performs theoperation of H′ (x, y)=H (x, y)+C₁₅₀ (x, y), thereby generating thephase distortion corrected pattern H′ (x, y).

(Fourth Modification)

The measuring equipment 70 may be used to measure the wavefrontdistortion resulting from the reading light source 10, the spatialfilter 20, the collimate lens 30, and the reading-side transparentsubstrate 150 b of PAL-SLM 150 in advance, respectively. Morespecifically, the measuring equipment 70 is connected to the controller60 as shown in FIG. 11, in the distortion-correction pattern formingprocess (FIG. 9(A), FIG. 9(B)). In the measuring process (S10), thereading light source 10, the spatial filter 20, the collimate lens 30,the phase modulation module 40, and the PAL-SLM 150 are placed in turnin the measuring equipment 70, so that the wavefront distortion due toeach member is measured. With respect to the reading light source 10,the wavefront detector 220 detects the wavefront distortion due to thereading light source 10. The wavefront detector 220 detects thewavefront distortion of the reading light emitted from the spatialfilter 20. The wavefront distortion due to the collimate lens 30 ismeasured in the same way as that of the spatial filter 20. As for thephase modulation module 40 and the PAL-SLM 150, the wavefront distortionis measured in the same manner as those in the third modification.

Assume that phase distortion patterns Φ₁₀ (x, y), Φ₂₀ (x, y), Φ₃₀ (x,y), and Φ₁₅₀ (x, y) have been measured for the reading light source 10,the spatial filter 20, the collimate lens 30, and the PAL-SLM 150,respectively. Then, these phase distortion pattern data Φ₁₀ (x, y), Φ₂₀(x, y), Φ₃₀ (x, y) and Φ₁₅₀ (x, y) is sent to the distortion patternmemory unit 60 b through the distortion pattern input unit 60 h (S10).

In the pattern-calculating process S20 (FIG. 9(B)), thedistortion-correction pattern generating unit 60 c reads the data Φ₁₀(x, y), Φ₂₀ (x, y), Φ₃₀ (x, y), and Φ₁₅₀ (x, y) from the distortionpattern memory unit 60 b. The unit 60 c then generates phase distortioncorrection patterns C₁₀ (x, y), C₂₀ (x, y), C₃₀ (x, y), and C₁₅₀ (x, y)for correcting the phase distortion patterns in accordance with thefollowing equations (2):C ₁₀(x, y)=−Φ₁₀(x, y)C ₂₀(x, y)=−Φ₂₀(x, y)C ₃₀(x, y)=−Φ₃₀(x, y)C ₁₅₀(x, y)=−Φ₁₅₀(x, y)  (2)

The resultant phase distortion correction patterns C₁₀ (x, y), C₂₀ (x,y), C₃₀ (x, y), and C₁₅₀ (x, y) are stored into thedistortion-correction pattern memory unit 60 d (S28).

In the modulation process (FIG. 7(A), FIG. 7(B)), the adder unit 60 ereads all the phase distortion correction pattern data C₁₀ (x, y), C₂₀(x, y), C₃₀ (x, y), and C₁₅₀ (x, y) from the distortion-correctionpattern memory unit 60 d (S3). The unit 60 e adds all the phasedistortion correction pattern data C₁₀ (x, y), C₂₀ (x, y), C₃₀ (x, y),and C₁₅₀ (x, y) to a desired CGH pattern H (x, y), thus generating aphase distortion corrected pattern H′ (x, y) (S4). In other words, theadder unit 60 e performs the operation of H′ (x, y)=H (x, y)+C₁₀ (x,y)+C₂₀ (x, y)+C₃₀ (x, Y)+C₁₅₀ (x, y), thereby generating a phasedistortion corrected pattern H′ (x, y).

(Fifth Modification)

In this modification, the measuring equipment 70 is arranged as shown inFIG. 11 in order to generate a phase distortion correction pattern C₁₅₀(x, y) (=−Φ₁₅₀ (x, y)) for correcting the wavefront distortion Φ₁₅₀ (x,y) that has resulted from the reading-side transparent substrate 150 bof PAL-SLM 150. The phase modulation module 40 or the PAL-SLM 150 isplaced in the measuring equipment 70, so that the distortion correctionpattern generating process of FIG. 9(A) and FIG. 9(B)) is carried out togenerate the phase distortion correction pattern C₁₅₀ (x, y). Togenerate a phase distortion correction pattern C₁ (x, y) (=−Φ₁ (x, y))for correcting the wavefront distortion Φ₁ (x, y) that has resulted fromthe reading light source 10, the spatial filter 20, and the collimatelens 30, the wavefront detector 210 is first placed as shown in FIG. 8.Then, the distortion correction pattern generating process of FIGS. 9(A)and 9(B) is performed, thereby generating the phase distortioncorrection pattern C₁ (x, y). As a result, the phase distortioncorrection pattern C₁₅₀ (x, y) is stored as the first phase distortioncorrection pattern into the distortion-correction pattern memory unit 60d. The phase distortion correction pattern C₁ (x, y) is stored as thesecond phase distortion correction pattern into thedistortion-correction pattern memory unit 60 d.

In the modulation process (FIG. 7(A), FIG. 7(B)), the adder unit 60 ereads the first phase distortion correction pattern C₁ (x, y) and thesecond phase distortion correction pattern C₁₅₀ (x, y) from thedistortion-correction pattern memory unit 60 d (S3) to add the first andsecond phase distortion correction patterns C₁ (x, y) and C₁₅₀ (x, y) toa desired CGH pattern H (x, y), thereby generating a phase distortioncorrected pattern H′ (x, y) (S4). In other words, the adder unit 60 eperforms the operation of H′ (x, y)=C₁ (x, y)+C₁₅₀ (x, y)+H (x, y),thereby generating a phase distortion corrected pattern H′ (x, y).

In the present modification, the beam sampler 200 and the wavefrontdetector 210 may be removable from the laser process apparatus 1.Alternatively, the beam sampler 200 and the wavefront detector 210 maybe installed in the apparatus 1 as in the first modification.

Second Embodiment

A laser process apparatus 1 and a laser process method according to thesecond embodiment of the invention will be described with reference toFIG. 12.

In this embodiment, as shown in FIG. 12, the controller 60 furtherincludes a distortion-correction pattern input unit 60 k. Thedistortion-correction pattern input unit 60 k is constituted by either arecording-medium reading device 65 or an NCU 67. The unit 60 k receivesthe distortion correction pattern C (x, y) from the network 68 or arecording medium 74 such as a flexible disk, a CD-ROM or a DVD to storethe distortion correction pattern in the distortion-correction patternmemory unit 60 d. In the present embodiment, the controller 60 does nothave the distortion pattern input unit 60 h, the distortion patternmemory unit 60 b and the distortion-correction pattern generating unit60 c. The controller 60 does not perform the distortion-correctionpattern generating process (FIG. 9(A), FIG. 9(B)) which is carried outin the first embodiment. Instead, a manufacturer of the laser processapparatus 1 performs the distortion-correction pattern process (FIG.9(A), FIG. 9(B)) before operating the laser process apparatus 1. In thiscase, the manufacturer prepares a computer 72 which is providedseparately from the controller 60. The manufacturer prepares measuringequipment 70 to connect the wavefront detector 220 in the measuringequipment 70 to the computer 72.

More precisely, in the preset embodiment, the manufacturer of the laserprocess apparatus 1 generates the distortion correction pattern C₁ (x,y) for correcting the wavefront distortion Φ₁ (x, y) due to the readinglight source 10, the spatial filter 20, and the collimate lens 30,before arranging these optical components 10, 20 and 30 to manufacturethe laser process apparatus 1. That is, the manufacturer first arrangesthe reading light source 10, the spatial filter 20, and the collimatelens 30 in the same positional relation as those in the laser processapparatus 1, as illustrated in FIG. 1, and then inserts these componentsas samples into the measuring equipment 70. Using the computer 72, themanufacturer carries out the process of generating adistortion-correction pattern (FIG. 9(A), FIG. 9(B)).

To be more specific, the measuring process (S10) shown in FIG. 9(A) isfirst carried out. The reading light source 10 is turned on, and thewavefront detector 220 measures the phase distortion pattern Φ₁ (x, y)of the light emitted from the collimate lens 30. The measured pattern Φ₁(x, y) is stored in the computer 72. The computer 72 performs thepattern-calculating process (S20) shown in FIG. 9(B) to calculate aphase distortion correction pattern C₁ (x, y)=−Φ₁ (x, y) (S26). In stepS28, the computer 72 stores the phase distortion correction pattern dataC₁ (x, y) in the recording medium 74 such as a flexible disk, a CD-ROM,or a DVD. Alternatively, the computer 72 stores the data C₁ (x, y) andthe program for generating distortion corrected patterns (pattern-addingprocess S1 shown in FIG. 7(B)) as an integrated package in the recordingmedium. The manufacturer provides a user with a combination of the laserprocess apparatus 1 and the recording medium 74. The user stores thephase distortion correction pattern data C₁ (x, y) in thedistortion-correction pattern memory unit 60 d from the recording medium74 through the distortion-correction pattern input unit 60 k. The usercan read the program for generating distortion corrected patternsthrough the reading device 65 to store the program in the hard diskdrive 61.

In step S28, the computer 72 may upload the phase distortion correctionpattern data C₁ (x, y) or an integrated package composed of the data C₁(x, y) and the program for generating distortion corrected patterns tothe network 68. In this case, the user downloads the phase distortioncorrection pattern data C₁ (x, y) from the network 68 through thedistortion-correction pattern input unit 60 k to store the downloadeddata into the distortion-correction pattern memory unit 60 d. The usercan download the program for generating distortion corrected patternsfrom the network 68 through the NCU 67 to store the program.

The laser process apparatus 1 which is provided to the user in the abovemanner performs the modulation process of FIGS. 7(A) and 7(B) in thesame way as that of the first embodiment. That is to say, a desired CGHpattern H (x, y) is read from the pattern memory unit 60 a, and thephase distortion correction pattern C₁ (x, y) is read from thedistortion-correction pattern memory unit 60 d. Then, these patterns areadded together to generate a phase distortion corrected pattern H′ (x,y), which is then used in the phase modulation process.

(First Modification)

Before arranging the reading light source 10, the spatial filter 20, thecollimate lens 30 and the phase modulation module 40 to manufacture thelaser process apparatus 1, the manufacturer may obtain a distortioncorrection pattern C₂ (x, y) for correcting the wavefront distortion Φ₂(x, y) resulting from the optical components 10, 20, 30 and 150 b. Inother words, the manufacturer first arranges the reading light source10, the spatial filter 20, the collimate lens 30, and the phasemodulation module 40 in the same manner as those of the laser processapparatus 1 (FIG. 1), and then loads the above components into themeasuring equipment 70 as samples. Next, the measuring process (S10)shown in FIG. 9(A) is started. The reading light source 10 is turned on,and then the wavefront detector 220 measures the phase distortionpattern Φ₂ (x, y) of the light emitted from the PAL-SLM 150. The phasemodulation module 40 remains off while the detector 220 is measuring thepattern Φ₂ (x, y). That is, the writing light source 110 remains off. Nodrive signals are applied to the LCD 130, and no AC voltage is appliedto the PAL-SLM 150. The results of the measuring are stored into thecomputer 72. The computer 72 performs the pattern-calculating process(S20) shown in FIG. 9(B) to calculate a phase distortion correctionpattern C₂ (x, y)=−Φ₂ (x, y) (S26). The computer 72 stores only thephase distortion correction pattern data C₂ (x, y) into the recordingmedium 74 such as a flexible disk, a CD-ROM or a DVD (S28).Alternatively, the computer 72 stores the integrated package composed ofthe data C₂ (x, y) and the program for generating distortion correctedpatterns (the pattern-adding process S1 shown in FIG. 7(B)) into themedium 74. The manufacturer provides the user with a combination of thelaser process apparatus 1 and the recording medium 74.

Alternatively, the computer 72 may upload the phase distortioncorrection pattern data C₂ (x, y) singly or an integrated packagecomposed of the data C₂ (x, y) and the program for generating distortioncorrected patterns to the network 68. In this case, the user stores thephase distortion correction pattern data C₂ (x, y) into thedistortion-correction pattern memory unit 60 d from the recording medium74 or the network 68 through the distortion-correction pattern inputunit 60 k. Further, the user can store the program for generatingdistortion corrected patterns into the hard disk drive 61 from thenetwork 68 or the recording medium 74.

The laser process apparatus 1 provided to the user in the abovedescribed manner performs the phase modulation process of FIGS. 7(A) and7(B) in the same way as that of the second modification of the firstembodiment. Namely, a desired CGH pattern H (x, y) is read from thepattern memory unit 60 a, and the phase distortion correction pattern C₂(x, y) is read from the distortion-correction pattern memory unit 60 d.Then, these patterns are added together to generate a phase distortioncorrected pattern H′ (x, y), which is used in the phase modulationprocess.

(Second Modification)

Before arranging the phase modulating module 40 to manufacture the laserprocess apparatus 1, the manufacturer may obtain a distortion correctionpattern C₁₅₀ (x, y) for correcting the wavefront distortion Φ₁₅₀ (x, y)resulting from the reading-side transparent substrate 150 b of PAL-SLM150. That is, the manufacturer first arranges the phase modulationmodule 40 or the PAL-SLM 150 in the measuring equipment 70 in the samemanner as that of the third modification of the first embodiment. Then,the measuring process (S10) shown in FIG. 9(A) is carried out, so thatthe wavefront detector 220 measures the phase distortion pattern Φ₁₅₀(x, y) of the light emitted from the PAL-SLM 150 that is not activated.The result of the measuring, Φ₁₅₀ (x, y), is stored into the computer72. The computer 72 performs the pattern-calculating process (S20) shownin FIG. 9(B) to calculate a phase distortion correction pattern C₁₅₀ (x,y)=−Φ₁₅₀ (x, y) (S26). The computer 72 stores the phase distortioncorrection pattern data C₁₅₀ (x, y) singly into the recording medium 74such as a flexible disk, a CD-ROM or a DVD (S28). The computer 72 mayalternatively store an integral package composed of the data C₁₅₀ (x, y)and the program for generating distortion corrected patterns (thepattern-adding process S1 shown in FIG. 7(B)) into the medium 74. Themanufacturer provides the user with a combination of the laser processapparatus 1 and the recording medium 74. Alternatively, the computer 72may upload the phase distortion correction pattern data C₁₅₀ (x, y)singly or an integral package composed of the data C₁₅₀ (x, y) and theprogram for generating distortion corrected patterns to the network 68.The user stores the phase distortion correction pattern data C₁₅₀ (x, y)into the distortion-correction pattern memory unit 60 d from therecording medium 74 or the network 68 through the distortion-correctionpattern input unit 60 k. Alternatively, the user can store the programfor generating distortion corrected patterns into the hard disk drive 61from the recording medium 74 or the network 68.

The laser process apparatus 1 provided to the user in the abovedescribed manner performs the modulation process of FIGS. 7(A) and 7(B)in the same way as that of the third modification of the firstembodiment. Namely, a desired CGH pattern H (x, y) is read from thepattern memory unit 60 a, and the phase distortion correction patternC₁₅₀ (x, y) is read from the distortion-correction pattern memory unit60 d. Then, these patterns are added together to generate a phasedistortion corrected pattern H′ (x, y), which is used in the phasemodulation process.

(Third Modification)

Before arranging the reading light source 10, the spatial filter 20, thecollimate lens 30, and the phase modulation module 40 to manufacture thelaser process apparatus 1, the manufacturer may obtain distortioncorrection patterns C₁₀ (x, y), C₂₀ (x, y), C₃₀ (x, y), and C₁₅₀ (x, y)for correcting the wavefront distortion Φ₁₀ (x, y), Φ₂₀ (x, y), Φ₃₀ (x,y), and Φ₁₅₀ (x, y) resulting from the optical components 10, 20, 30,and 150 b, respectively. That is, the manufacturer arranges the readinglight source 10, the spatial filter 20, the collimate lens 30, andeither one of the phase modulation module 40 and the PAL-SLM 150 whichare not activated in turn in the measuring equipment 70 in the samemanner as that of the fourth modification of the first embodiment. Then,the measuring process (S10) shown in FIG. 9(A) is carried out, so thatthe wavefront distortions Φ₁₀ (x, y), Φ₂₀ (x, y), Φ₃₀ (x, y), and Φ₁₅₀(x, y) are measured by the use of the wavefront detector 220. Theresults of the measuring Φ₁₀ (x, y), Φ₂₀ (x, y), Φ₃₀ (x, y) and Φ₁₅₀ (x,y) are stored into the computer 72. The computer 72 performs thepattern-calculating process (S20) shown in FIG. 9(B) to obtain a phasedistortion correction patterns C₁₀ (x, y)=−Φ₁₀ (x, y), C₂₀ (x, y)=Φ₂₀(x, y), C₃₀ (x, y)=−Φ₃₀ (x, y) and C₁₅₀ (x, y)=−DΦ₁₅₀ (x, y) (S26). Thecomputer 72 stores the phase distortion correction pattern data C₁₀ (x,y), C₂₀ (x, y), C₃₀ (x, y), and C₁₅₀ (x, y) singly into the recordingmedium 74 such as a flexible disk, a CD-ROM or a DVD. Alternatively, thecomputer 72 may store an integral package composed of these data and theprogram for generating distortion corrected patterns (the pattern-addingprocess S1 shown in FIG. 7(B)) into the medium 74 (S28). Themanufacturer provides the user with a combination of the laser processapparatus 1 and the recording medium 74. Alternatively, the computer 72may upload the phase distortion correction pattern data C₁₀ (x, y), C₂₀(x, y), C₃₀ (x, y), and C₁₅₀ (x, y), singly or an integral packagecomposed of these data and the program for generating distortioncorrected patterns to the network 68 in S28. The user stores the phasedistortion correction pattern data C₁₀ (x, y), C₂₀ (x, y), C₃₀ (x, y),and C₁₅₀ (x, y) into the distortion-correction pattern memory unit 60 dfrom the recording medium 74 or the network 68 through thedistortion-correction pattern input unit 60 k. Further, the user canstore the program for generating distortion corrected patterns into thehard disk drive 61 from the recording medium 74 or the network 68.

The laser process apparatus 1 provided to the user in the abovedescribed manner performs the modulation process of FIGS. 7(A) and 7(B)in the same way that of the fourth modification of the first embodiment.Namely, a desired CGH pattern H (x, y) is read from the pattern memoryunit 60 a, and the phase distortion correction patterns C₁₀ (x, y), C₂₀(x, Y), C₃₀ (x, y) and C₁₅₀ (x, y) are read from thedistortion-correction pattern memory unit 60 d. Then, these patterns areadded together, to generate a phase distortion corrected pattern H′ (x,y), which is used in the phase modulation process.

Third Embodiment

A laser process apparatus 1 and a laser process method according to thethird embodiment of the invention will be described with reference toFIG. 13.

In the present embodiment, as shown in FIG. 13, the controller 60 has adistortion-correction pattern input unit 60 k, similarly to the secondembodiment. As in the first embodiment, the controller 60 includes adistortion pattern input unit 60 h, a distortion pattern memory unit 60b, and a distortion-correction pattern generating unit 60 c.

In this embodiment, a manufacturer obtains a phase distortion correctionpattern C₁₅₀ (x, y) for correcting the wavefront distortion Φ₁₅₀ (x, y)(=−Φ₁₅₀ (x, y)) resulting from the reading-side transparent substrate150 b of PAL-SLM 150, before arranging the phase modulating module 40 tomanufacture the laser process apparatus 1 in the same manner as that ofthe second modification of the second embodiment. That is, themanufacturer first arranges the phase modulation module 40 or thePAL-SLM 150 in the measuring equipment 70. Using the computer 72, themanufacturer carries out the process for generating a distortioncorrection pattern (FIG. 9(A), FIG. 9(B)). The resultant first phasedistortion correction pattern C₁₅₀ (x, y) singly or an integral packagecomposed of the pattern C₁₅₀ (x, y) and one of the program forgenerating distortion corrected patterns (the pattern-adding process S1shown in FIG. 7(B)) and the program for generating distortion correctionpatterns (S20 shown in FIG. 9(B)) is stored into the recording medium 74such as a flexible disk, a CD-ROM or a DVD, or uploaded to the network68.

The user stores the first phase distortion correction pattern data C₁₅₀(x, y) into the distortion-correction pattern memory unit 60 d from therecording medium 74 or the network 68. Note that the user stores theprogram for generating distortion corrected patterns and the program forgenerating distortion correction patterns into the controller 60.

As is the case with the fifth modification of the first embodiment, theuser arranges the beam sampler 200 and the wavefront detector 210downstream of the collimate lens 30 to carry out the process ofgenerating a distortion correction pattern (FIG. 9(A), FIG. 9(B)).Accordingly, the wavefront detector 210 measures the wavefrontdistortion Φ₁ (x, y) resulting from the reading light source 10, thespatial filter 20, and the collimate lens 30. The wavefront distortiondata Φ₁ (x, y) is stored into the distortion pattern memory unit 60 bthrough the distortion pattern input unit 60 h. Thedistortion-correction pattern generating unit 60 c obtains a phasedistortion correction pattern C₁ (x, y) for correcting this wavefrontdistortion data Φ₁ (x, y) (=−C₁ (x, y)). The data C₁ (x, y) is stored asa second phase distortion correction pattern into thedistortion-correction pattern memory unit 60 d.

In this modification, the modulation process of FIGS. 7(A) and 7(B) isperformed in the same way as in the case of the fifth modification ofthe first embodiment. That is to say, a desired CGH pattern H (x, y) isread from the pattern memory unit 60 a, and the phase distortioncorrection patterns data C₁ (x, y) and C₁₅₀ (x, y) are read from thedistortion-correction pattern memory unit 60 d. Then, these patterns areadded together to generate a phase distortion corrected pattern H′ (x,y), which is used in the phase modulation process.

To form an image of letter “

” on the process target T, for example, the adder unit 60 e reads CGHpattern data H (x, y) for forming the letter “

” from the pattern memory unit 60 a. The adder unit 60 e reads the phasedistortion correction pattern data C₁ (x, y) and C₁₅₀ (x, y) from thedistortion-correction pattern memory unit 60 d. The adder unit 60 e addsthe CGH pattern data H (x, y) and the phase distortion correctionpattern data C₁ (x, y) and C₁₅₀ (x, y) to generate phase distortioncorrected pattern data H′ (x, y). The phase modulation module 40performs phase modulation process in accordance with the phasedistortion corrected pattern data H′ (x, y). Therefore, the letter “

” is formed without any distortion on the process target T, as isillustrated in FIG. 14(A).

If the CGH pattern H (x, y) for forming the letter “

” is not added to the phase distortion correction pattern C₁ (x, y)and/or the phase distortion correction pattern C₁₅₀ (x, y), and thephase modulation module 40 performs the phase modulation process on thebasis of the CGH pattern data H (x, y), a letter “

” is focused to form the image having distortion caused due to thewavefront distortion of the reading light on the process target T, asillustrated in FIG. 14(B). Note that FIGS. 14(A) and 14(B) show imagesphotographed by a CCD device that is placed at the position where theprocess target T should be located.

In this embodiment, the beam sampler 200 and the wavefront detector 210may be removably connected to the laser process apparatus 1 as in thecase of the first embodiment, or may be fixed in the apparatus 1 as inthe case of the first modification of the first embodiment.

A manufacturer of the laser process apparatus 1 may use the measuringequipment 70 and computer 72 beforehand as in the case of the secondembodiment to obtain the phase distortion correction pattern C₁ (x, y)for collecting the wavefront distortion data Φ₁ (x, y) (=−C₁ (x, y))resulting from the reading light source 10, the spatial filter 20, andthe collimate lens 30. In this case, either one, or combination of thephase distortion correction pattern data C₁ (x, y) and C₁₅₀ (x, y) canbe stored into the recording medium 74 singly or as an integral packagecomposed of these pattern data and the program for generating distortioncorrected patterns, or uploaded to the network 68.

Fourth Embodiment

A laser process apparatus and a laser process method according to thefourth embodiment of the invention will be described with reference toFIGS. 8 and 15.

In the laser process apparatus 1 of this embodiment, the beam sampler200 and the wavefront detector 210 are mounted in a similar manner tothe case of the first modification of the first embodiment as shown inFIG. 8. In other words, the laser process apparatus 1 according to thepresent embodiment includes a reading light source 10, a spatial filter20, a collimate lens 30, a phase modulation module 40, a Fourier lens50, a controller 60, a beam sampler 200, and a wavefront detector 210,as is illustrated in FIG. 8. The beam sampler 200 is provided downstreamof the collimate lens 30 to reflect part of the incident light andguides the reflected light to the wavefront detector 210. The controller60 has the same configuration as that of the first embodiment (FIG. 2and FIG. 4). In FIG. 8, only the components 60 g and 60 h of thecontroller 60 are illustrated, the other components 60 a to 60 f, 60 iand 60 j are omitted.

The present embodiment differs from the first embodiment in that theprogram for generating distortion correction patterns and performing themodulation process which is shown in FIG. 15 is stored in the hard diskdrive 61 or ROM 64 (FIG. 2) instead of the program for generatingdistortion correction patterns (FIGS. 9(A) and 9(B)) and the program forperforming the modulation (FIGS. 7(A) and 7(B)). The program forgenerating distortion correction patterns and performing the modulationmay be stored in a recording medium in advance, and then stored in thehard disk drive 61 through the reading device 65. Alternatively, theprogram may be uploaded to the network 68 and then downloaded via theNCU 67.

In the laser process apparatus 1, the laser light from the reading lightsource 10 sometimes has dynamic fluctuation. In addition, air in theoptical path extending from the reading light source 10 to the collimatelens 30 through the spatial filter 20 may vibrate. In these case, thewavefront distortion occurring downstream of the collimate lens 30(i.e., distortion indicated by the curving line in FIG. 8) contains thedynamic wavefront distortion, as well as the static wavefront distortionresulting from the structures of the reading light source 10, thespatial filter 20, and the collimate lens 30.

Hence, in the present embodiment, in order to remove the dynamicwavefront distortion as well as the static wavefront distortion, themeasurement of the phase distortion Φ₁ (x, y) at the wavefront of thereading light is repeated during the phase modulation to send the resultof measurement periodically to the controller 60. The controller 60generates phase distortion correction pattern data C₁ (x, y) based onthe received measuring result Φ₁ (x, y) and then adds the phasedistortion correction pattern data C₁ (x, y) to a desired CGH patterndata H (x, y) to obtain the phase distortion corrected pattern data H′(x, y). Thus, the modulation is performed by repeating update of thephase distortion corrected pattern H′ (x, y) on the basis of the latestmeasurement of the phase distortion Φ₁ (x, y).

To be more specific, in this embodiment, the wavefront detector 210performs real-time measurement of the wavefront distortion occurringdownstream of the collimate lens 30 to repeatedly send the resultantphase distortion pattern data Φ₁ (x, y) to the controller 60. In thisembodiment, note that the resultant phase distortion pattern Φ₁ (x, y)contains both the static distortion and the dynamic distortion resultingfrom the optical components that are arranged upstream of the beamsampler 200 (the reading light source 10, the spatial filter 20, and thecollimate lens 30). Note that the beam sampler 200 passes and guidesmost of the incident light to the phase modulation module 40, so thatmost of the reading light from the reading light source 10 can be usedfor is the target processing.

The operation of the laser process apparatus 1 of this embodiment(generation of a distortion correction pattern and phase modulation)will be described with reference to FIG. 15.

Before instructing the controller 60 to perform the generation of adistortion correction pattern and the phase modulation (targetprocessing), a user starts driving the reading light source 10 and thewriting light source 110. At the same time, the user instructs thewavefront detector 210 to repeat detection of a wavefront repeatedly atprescribed intervals. According to the above instruction, the wavefrontdetector 210 performs the first detection of a wavefront to input theresultant phase distortion pattern data Φ₁ (x, y) to the controller 60.

Next, the user instructs the controller 60 to perform the targetprocessing. The controller 60 then reads the CGH pattern H (x, y) to beused for the target processing from the pattern memory unit 60 a (S50).

Then, it is determined whether or not the controller 60 received thelatest measured distortion pattern Φ₁ (x, y) from the wavefront detector21. In this case, since the controller 60 receives the result of thefirst wavefront detection (Yes in S52), the phase distortion patterndata Φ₁ (x, y) is stored into the distortion pattern memory unit 60 b(S54).

Next, the distortion-correction pattern generating unit 60 c generates aphase distortion correction pattern C₁ (x, y)=−Φ₁ (x, y) (S56) to storethe pattern C₁ (x, y) into the distortion-correction pattern memory unit60 d (S58).

Thereafter, the adder unit 60 e adds the CGH pattern H (x, y) and thephase distortion correction pattern C₁ (x, y) (S62). If the result ofthe addition has a negative value or another value equal to or greaterthan 2π, the adder unit 60 e performs the phase turn-up process as inthe case of the step S4 in the first embodiment. The adder unit 60 estores the resultant phase distortion corrected pattern H′ (x, y) intothe distortion-corrected pattern memory unit 60 f (S64).

The control unit 60 g generates a drive signal on the basis of the phasedistortion corrected pattern H′ (x, y) and starts supplying the drivesignal to the LCD 130 to start the drive process (S66).

When the drive operation (i.e., process) is started as the above manner,it is determined whether the target processing is terminated, that is,whether a preset process time has elapsed since the start of the driveprocess (S68). If the preset process time has not elapsed (No in S68),the operation returns to S52. Note that the control unit 60 g keepssupplying the drive signal generated in S66 to the LCD 130 until thedrive signal is updated next time.

The wavefront detector 210 repeats the detection of the wavefront at theprescribed intervals. The intervals are significantly shorter than thepreset processing time, and longer than the time that the controller 60requires to carry out one sequence of steps S52 to S68. Every time thewavefront detector 210 performs one detection of the wavefront, thewavefront detector 210 sends the resultant phase distortion pattern dataΦ₁ (x, y) to the controller 60.

When the process returns to step S52, the controller 60 determineswhether the latest measured phase distortion pattern data Φ₁ (x, y) hasbeen input from the wavefront detector 210. If the data has not beeninput (No in S52), the controller 60 waits until the data is input. Ifthe data has been input (Yes in S52), the latest phase distortionpattern Φ₁ (x, y) sent to the controller 60 is stored (S54) to renew aphase distortion correction pattern data C₁ (x, y) (S56, S58). The adderunit 60 e adds the renewed phase distortion correction pattern C₁ (x, y)to the desired phase pattern data H (x, y) to generate a new phasedistortion corrected pattern H′ (x, y) (S62, S64). The control unit 60 gupdates the drive signal (S66) in accordance with the newphase-distortion corrected pattern H′ (x, y). The control unit 60 gsupplies the drive signal updated above to the phase modulation module40 to keep performing the drive process (target processing). Thus, theoperation consisting of the steps S56 to S68 is repeated.

As described above, every time the latest measured phase distortionpattern data Φ₁ (x, y) is received by the controller 60 from thewavefront detector 210, the phase distortion correction pattern C₁ (x,y) is updated. The updated phase distortion correction pattern C₁ (x, y)is added to the desired phase pattern data H (x, y) to generate a phasedistortion corrected pattern H′ (x, y). The drive signal is renewed inaccordance with the phase distortion corrected pattern H′ (x, y) so thatthe target processing is continued on the basis of the renewed the drivesignal. Thus, the drive signal is renewed and supplied to the LCD 130,every time the latest measured phase distortion pattern data Φ₁ (x, y)is received.

If the preset process time period has elapsed since the start of thedrive process (target processing), and reached the timing that the driveprocess should be over (Yes in S68), the control unit 60 g stopssupplying the drive signal to terminate the drive process (S70), andthen terminate the target processing. Both the reading light source 10and the writing light source 110 are turned off.

Thus, according to the present embodiment, the phase modulation module40 can be driven with the phase distortion corrected pattern H′ (x, y)which has corrected the latest measured wavefront distortion Φ₁ (x, y).Hence, not only the static distortion but also the dynamic distortioncan be reliably corrected, so that the phase-modulated light having thedesired CGH pattern H (x, y) can be generated with higher accuracy.

Moreover, in the present embodiment, the phase distortion correctionpattern C₁ (x, y) is renewed and the phase distortion corrected patternH′ (x, y) is renewed, every time the controller 60 receives the phasedistortion pattern Φ₁ (x, y) measured by the wavefront detector 210. Thetarget processing is continued in accordance with the renewed phasedistortion corrected pattern H′ (x, y). That is, the controller 60renews the phase distortion corrected pattern H′ (x, y) to modify thetarget processing, every time the wavefront detector 210 performs onedetection operation to generate a phase distortion pattern Φ₁ (x, y).Therefore, a real-time control can be accomplished with high precision.

In the above explanation, the detection cycle of the wavefront detector210 is longer than the time period for the controller 60 to perform onesequence of steps S52 to S68. However, if the detection cycle and timingof the wavefront detector 210 is set identical to the time and timingrequired for the controller 60 to perform the sequence of steps S52 toS68, the decision made in step S52 can be always “Yes.”

(First Modification)

The first modification of the present embodiment will be describedbelow.

In this modification, the controller 60 has the configuration of FIG. 13as in the case of the third embodiment. Note that the beam sampler 200and the wavefront detector 210 are fixed in the laser process apparatus1.

In the present modification, the manufacturer uses the measuringequipment 70 to measure a distortion pattern Φ₁₅₀ (x, y) resulting fromthe reading-side transparent substrate 150 b of PAL-SLM 150, beforearranging the phase modulating module 40 as in the case of the thirdembodiment to manufacture the laser process apparatus 1. Themanufacturer then uses the computer 72 to obtain a phase distortioncorrection pattern C₁₅₀ (x, y) (=−Φ₁₅₀ (x, y)). The computer 72 recordsthe phase distortion correction pattern data C₁₅₀ (x, y) as a firstphase distortion correction pattern in the recording medium 74 such as aflexible disk, a CD-ROM or a DVD. The first phase distortion correctionpattern data C₁₅₀ (x, y) may be recorded together with the program forgenerating the distortion correction patterns and performing themodulation (FIG. 15) in the form of a package. The manufacturer providesthe user with a combination of the laser process apparatus 1 and therecording medium 74. Alternatively, the manufacturer may upload to thenetwork 68 the first phase distortion correction pattern C₁₅₀ (x, y)singly or an integral package including the pattern C₁₅₀ (x, y) and theprogram for generating the distortion correction patterns and performingthe modulation (FIG. 15). The user stores the first phase distortioncorrection pattern data C₁₅₀ (x, y) into the distortion-correctionpattern memory unit 60 d through the reading device 65 or the NCU 67(the distortion-correction pattern input unit 60 k).

In accordance with the user's instruction for the target processing, thecontroller 60 causes the beam sampler 200 and wavefront detector 210 inthe laser process apparatus 1 to measure the distortion Φ₁ (x, y)occurring downstream of the collimate lens 30 repeatedly in real time.Thus, the phase distortion correction pattern C₁ (x, y) (=−Φ₁ (x, y)) asa second phase-distortion correction pattern is repeatedly renewed.

Namely, the controller 60 performs the process for generating thedistortion correction patterns and performing the modulation of FIG. 15,as will be described below.

If the phase distortion pattern Φ₁ (x, y) is received from the wavefrontdetector 210 (Yes in S52), the phase distortion pattern data Φ₁ (x, y)is stored in the distortion pattern memory unit 60 b (S54). Thereafter,a phase-distortion correction pattern data C₁ (x, y) (=−Φ₁ (x, y)) isobtained as the second phase distortion correction pattern (S56) to bestored into the distortion-correction pattern memory unit 60 d (S58).

The phase distortion correction pattern data C₁₅₀ (x, y) for correctingthe static distortion resulting from the reading-side transparentsubstrate 150 b of PAL-SLM 150 is already stored in thedistortion-correction pattern memory unit 60 d stores as a firstphase-distortion correction pattern. Therefore, in step S62, the adderunit 60 e adds the first phase distortion correction pattern data C₁₅₀(x, y) and the second phase distortion correction pattern data C₁ (x, y)to a desired CGH pattern data H (x, y). Thus, the phase distortioncorrected pattern data H′ (x, y) is obtained, and the drive signal isrenewed. The phase distortion corrected pattern data H′ (x, y) and therenewed drive signal are supplied to the LCD 130.

In this modification, the static distortion resulting from the opticalcomponents 10 to 30, the static distortion resulting from thereading-side transparent substrate 150 b of PAL-SLM 150, and the dynamicdistortion resulting from the optical path defined by the opticalcomponents 10 to 30 can be reliably removed. Accordingly, it is possibleto generate phase-modulated light at high precision.

(Second Modification)

In the present modification, the controller 60 has the configuration ofFIG. 10 as in the case of the second modification of the firstembodiment. The beam sampler 200 and the wavefront detector 210 areplaced and fixed in the laser process apparatus 1.

In the laser process apparatus 1, if air vibrates in the optical pathextending along the optical components 30 and 40, the wavefrontdistortion occurring downstream of the phase modulation module 40 (thedistortion indicated by the curving line in FIG. 10) contains dynamicdistortion. To remove such dynamic distortion, it is sufficient toperform the process of generating the distortion correction pattern andperforming the modulation of the present embodiment (FIG. 15) when thebeam sampler 200 is arranged downstream of the phase modulation module40 as illustrated in FIG. 10. In this modification, the staticdistortion resulting from the structures of the optical components 10 to30 and 150 b and the dynamic distortion resulting from the optical pathextending along the optical components 10 and 40 can be reliablyremoved. It is therefore possible to generate light that isphase-modulated with a desired phase pattern H (x, y) at high precision.

To perform the process of generating the distortion correction patternsand performing the modulation of FIG. 15 in the present modification,the control unit 60 g keeps the phase modulation module 40 off while thewavefront detector 210 is operating. That is, the control unit 60 gsuspends supplying the drive signal to the LCD 130, turns off thewriting light source 110, and suspends applying an AC voltage to thePAL-SLM 150. When the wavefront detector 210 operates while the phasemodulation module 40 remains on, the detected wavefront pattern maycontain the wavefront distortion due to the CGH pattern displayed on thephase modulation module 40. In this case, it is impossible to detect thewavefront distortion resulting from only the optical components and theoptical path independently of the wavefront distortion due to the CGHpattern.

If the dynamic distortion occurs at any position in the optical pathother than the phase modulation module 40, it is possible to arrange thebeam sampler 200 and the wavefront detector 210 so as to detect thedynamic distortion at that position, and then to carry out the processof generating distortion the correction patterns and performing themodulation (FIG. 15). The dynamic distortion can be removed by measuringthe dynamic distortion in real time and repeatedly supplying theresultant dynamic distortion to the controller 60.

Fifth Embodiment

The first to fourth embodiments described above are made by applying aphase modulating apparatus and a phase modulating method according tothe present invention to a laser process apparatus and a laser processmethod. However, the phase modulating apparatus and phase modulatingmethod of the present invention can be applicable to any phasemodulating apparatus and phase modulating method that use a phasemodulation module 40 to phase-modulate reading light as well as thelaser process apparatus and method. It is possible to measure awavefront distortion resulting from optical components such as the phasemodulation module 40 and the optical path in real time or in advance tocalculate a wavefront-distortion correction pattern for correcting themeasured wavefront distortion and then add the calculatedwavefront-distortion correction pattern to a desired phase pattern.

More specifically, before shipping the phase modulation module 40, themanufacturer of the phase modulation module 40 uses the measuringequipment 70 to generate a wavefront distortion pattern Φ₁₅₀ (x, y)resulting from the reading-side transparent substrate 150 b of PAL-SLM150 of each phase modulation module 40. The way to measure the wavefrontdistortion pattern Φ₁₅₀ (x, y) is the same as that of the secondmodification of the second embodiment (FIG. 12). The computer 72calculates a phase distortion correction pattern C₁₅₀ (x, y)=−Φ₁₅₀ (x,y) on the basis of the measuring result Φ₁₅₀ (x, y). The resultant phasedistortion correction pattern data C₁₅₀ (x, y) is stored in therecording medium 74 such as a flexible disk, a CD-ROM, or a DVD in theform of an integral package with the program for generating thedistortion corrected patterns (the pattern-adding process S1 shown inFIG. 7(B)) and the drive program (the drive process S7 shown in FIG.7(A)). The manufacturer then provides the recording medium 74 to theuser in combination with the phase modulation module 40.

A user assembles a desired phase modulating apparatus with the phasemodulation module 40. The phase modulating apparatus may have anidentical configuration to the laser process apparatus 1 shown in FIG.12. The phase modulating apparatus may be formed by placing a processtarget T on the Fourier plane of the Fourier-transform lens 50 or byplacing a desired device such as an imaging device for acquiring aFourier-transform image. Note that the controller 60 has the structureshown in FIG. 12, for example. The user stores the phase distortioncorrection pattern data C₁₅₀ (x, y), the program for generating thedistortion corrected patterns (the pattern-adding process S1 of FIG.7(B)), and the drive program (the drive process S7 of FIG. 7(A)) intothe controller 60. As a result, the controller 60 can perform the phasemodulation of FIGS. 7(A) and 7(B). In other words, the controller 60adds the desired CGH pattern H (x, y) and the phase distortioncorrection pattern C₁₅₀ (x, y) together to generate a phase distortioncorrected pattern data H′ (x, y), thereby performing the phasemodulation.

As described above, the recording medium 74 stores the phase distortioncorrection pattern C₁₅₀ (x, y) inherent to the reading-side transparentsubstrate 150 b of PAL-SLM 150 in the phase modulation module 40, theprogram for generating the distortion corrected patterns (FIG. 7(B)),and the drive program. By combining the above recording medium 74 withthe phase modulation module 40, the user can phase-modulate light fastand quickly in accordance with the distortion corrected pattern withoutmeasuring the wavefront distortion of the incident light to the PAL-SLM150, when phase modulation of light is performed by using the phasemodulating apparatus incorporating the PAL-SLM 150.

Using this phase modulation module 40, the user can produce any type ofphase modulating apparatus such as an apparatus for generatinghologram-reproducing patterns or a wave-shaping apparatus for use with afemtosecond laser.

The following description will be made for explaining the case in whicha wave-shaping apparatus for use with a femtosecond laser ismanufactured by using the phase modulation module 40, with reference toFIG. 16.

Note that the wave-shaping apparatus for use with a femtosecond laser isan apparatus that separates a femtosecond laser beam into spectra tomodulate each spectrum at the spectral plane, thereby shaping a pulseshape or a pulse width.

The wave-shaping apparatus 300 for use with the femtosecond laser beamincludes a first grating 310, a first cylindrical mirror 320, a phasemodulation module 40, a second cylindrical mirror 330, a second grating340, an output mirror 350, and a controller 60. The phase modulationmodule 40 has the same configuration as that of FIG. 3. The controller60 has the configuration as shown in in FIG. 12. After producing thewave-shaping apparatus 300 for use with the femtosecond laser, a userstores the phase distortion correction pattern data C₁₅₀ (x, y) from therecording medium 74 or the network 68 into the distortion-correctionpattern memory unit 60 d in the controller 60. The user generates adesired phase pattern H (x, y) to stores the desired phase pattern H (x,y) into the pattern memory unit 60 a.

A femtosecond laser beam is divided into spectra by the first grating310, reflected by the first cylindrical mirror 320, and guided into tothe PAL-SLM 150 of the phase modulation module 40 in the same manner asthat of the case shown in FIG. 3. That is, the wavelength components ofthe femtosecond laser beam decomposed spacially are incident on thePAL-SLM 150. Note that the desired phase pattern H (x, y) stored in thepattern memory unit 60 a is used to phase-modulate each decomposedwavelength component on the xy plane in a particular manner. The adderunit 60 e in the controller 60 adds the phase pattern H (x, y) and thephase distortion correction pattern C₁₅₀ (x, y) together to generate aphase distortion corrected pattern H′ (x, y). In accordance with thephase distortion corrected pattern H′ (x, y), the control unit 60 ggenerates an LCD drive signal to drive the phase modulation module 40.As a result, the femtosecond laser beam is phase-modulated. Since thephase modulation module 40 is driven in accordance with the phasedistortion corrected pattern H′ (x, y) obtained by adding the phasedistortion correction pattern C₁₅₀ (x, y) to the desired phase pattern H(x, y), each wavelength component can be phase-modulated in a desiredmanner at high precision. Hence, a desired output pattern can begenerated at high precision. After the phase-modulated femtosecond laserbeam is reflected by the second cylindrical mirror 330, thephase-modulated femtosecond laser beam is changed by the second grating340 from the dispersed condition to the focused condition. Thephase-modulated femtosecond laser beam is then reflected by the outputmirror 350, and emitted outside. Thus, it is possible to emit afemtosecond laser beam that has been rectified pulse wave-shape or pulsewidth.

Note that the controller 60 may have any one of the structures shown inFIGS. 4, 8, and 10 to 13. The phase distortion Φ (x, y) resulting fromeach of the first grating 310, the first cylindrical mirror 320, thesecond cylindrical mirror 330, the second grating 340, and the outputmirror 350 is measured, respectively. And, the phase distortioncorrection pattern C (x, y), i.e., an inverse pattern of the measuredphase distortion pattern (−Φ (x, y)), in conjunction with the phasedistortion correction pattern C₁₅₀ (x, y) can be then added to thedesired phase pattern H (x, y). Alternatively, the phase distortion Φ(x, y) resulting from at least one or more of the optical components 310to 340 and the component 150 can be measured together. And the phasedistortion correction pattern(s) C (x, y), i.e., inverse pattern(s) ofthe measured the phase distortions (−Φ (x, y)) can be then added to thedesired phase pattern H (x, y). Alternatively, the measurement of thephase distortion Φ (x, y) may be repeated in real time so that themeasured results can be sent to the controller 60.

The phase modulating apparatus and phase modulating method according tothe present invention are not limited to the embodiments describedabove. Various changes and modifications can be made within the scope ofthe claims.

For example, the phase distortion Φ₅₀ (x, y) resulting from the Fourierlens 50 in the laser process apparatus 1 of FIG. 1 may be measured toobtain a phase distortion correction pattern C₅₀ (x, y) (=−Φ₅₀ (x, y)).The Fourier lens 50, for example, is set into the measuring equipment 70separately from other optical components to measure the phase distortionΦ₅₀ (x, y), thereby obtaining the phase distortion correction patternC₅₀ (x, y) (=−Φ₅₀ (x, y)). The phase distortion correction pattern C₅₀(x, y) can be added to the desired phase pattern H (x, y) along with thephase distortion correction patterns for the optical components 10 to 30and 150. Alternatively, the beam sampler 200 may be placed downstream ofthe Fourier lens 50 to measure the phase distortions Φ (x, y) resultingfrom the optical components 10, 20, 30, 150 and 50 together. A phasedistortion correction pattern C (x, y) (=−Φ (x, y)) is obtained to beadded to the desired phase pattern H (x, y). In this case, the phasedistortions Φ (x, y) may be measured in advance as the case of the firstto third embodiments. Alternatively, the phase distortions Φ (x, y) maybe repeatedly measured in real time as the case of the fourth embodimentto supply the phase distortion Φ (x, y) to the controller 60.

In the embodiments described above, when the phase distortion Φ₂ (x, y)or the phase distortion Φ₁₅₀ (x, y) resulting from the reading-sidetransparent substrate 150 b of PAL-SLM 150 of the phase modulationmodule 40 is measured, no drive signal is supplied to the LCD 130, thewriting light source 110 is turned off, and no AC voltage is applied tothe PAL-SLM 150 in order to deactivate the phase modulation module 40.However, it is sufficient not to apply the drive signal at least to theLCD 130. The writing light source 110 may be turned on, and an ACvoltage may be applied to the PAL-SLM 150.

Similarly, in the embodiments described above, when the PAL-SLM 150 isset into the measuring equipment 70 and the phase distortion Φ₁₅₀ (x, y)resulting from the reading-side transparent substrate 150 b is measured,no AC voltage is applied to the PAL-SLM 150 and no writing light isirradiated in order to deactivate the PAL-SLM 150. However, it is properto prevent at least the writing light from impinging. An AC voltage canbe applied to the PAL-SLM 150.

In the fourth modification of the first embodiment, the wavefrontdistortions resulting from the reading light source 10, the spatialfilter 20, the collimate lens 30, and the reading-side transparentsubstrate 150 b of PAL-SLM 150 are first measured in advanceindependently from each other by the use of the measuring equipment 70,respectively to obtain the correction patterns for correcting thesewavefront distortions and then adding the correction patterns to thedesired phase pattern. Instead, the wavefront distortions resulting fromthe reading light source 10, the spatial filter 20, and the collimatelens 30 may be first obtained independently of each other by using themeasuring equipment 70. And, the correction patterns for correctingthese wavefront distortions may be then obtained to be added to thedesired phase pattern.

In the embodiments described above, the phase turn-up process (S4 inFIG. 7(B) and S62 in FIG. 15) is performed when the CGH pattern H (x, y)and the phase distortion correction pattern C (x, y) are added together.However, the phase turn-up process may be carried out, when the phasedistortion correction pattern C (x, y) (S26 in FIG. 9(B), and S56 inFIG. 15) is generated as well as addition of the patterns. That is, thesign of the phase distortion pattern Φ (x, y) is inverted to generatethe phase distortion correction pattern C (x, y). And the phase value C(x, y) of a given pixel (x, y) may be replaced with the remainderobtained by dividing the phase value C by 2π, when the phase value C forany pixel (x, y) is equal to or greater than 2π, or less than zero.Further, the phase turn-up process may be carried out for the CGHpattern H (x, y) in advance. And the phase value H (x, y) at a givenpixel (x, y) may be replaced with the remainder obtained by dividing thephase value H by 2π, when the phase value H is equal to or greater than2π, or less than zero.

In the first to the fourth embodiments, the desired phase pattern H (x,y) is a hologram pattern. The desired phase pattern H (x, y) may be anyother type of phase pattern rather than a hologram.

The configuration of the phase modulation module 40 is not limited tothe one described above. For example, the LCD 130 and the PAL-SLM can beconnected together through an optical fiber plate instead of the relaylens 140 as disclosed in International Publication No. WO99/66368. Thatis, the writing-side transparent substrate 150 a is removed from thePAL-SLM 150, and the transparent electrodes 150 c is connected to thelight-transmitting layer 130 b of the LCD 130 by the optical fiberplate. In this case, provided that the numerical aperture NA_(FOP) ofthe optical fiber plate has the relation of n_(G)·P/d<NA_(FOP)<2n_(G)·P/d, where P is the pixel pitch in the LCD 130, d is the thicknessof the light-transmitting layer 130 b, and n_(G) is the refractive indexof the layer 130 b at a wavelength λ of light emitted from the writinglight source 110, the optical fiber plate can accurately transmit thephase distortion corrected pattern H′ (x, y) displayed on the LCD 130 tothe PAL-SLM 150, while eliminating the signal component due to the pixelassembly layer 130 c of the LCD 130.

Furthermore, the configuration of the LCD 130 is not limited to the onedescribed above. Any type of liquid-crystal display can be used as theLCD 130.

For example, an LCD having a micro-lens array provided on thelight-receiving layer 130 a can be used as the LCD 130. In this case,the micro-lens array has a plurality of micro-lenses, which are arrangedin one-to-one correspondence to the transparent pixel electrodes of thepixel assembly layer 130 c. If such a LCD 130 is adopted, any signalcomponent due to the pixel assembly layer 130 c of the LCD 130 can beremoved by adjusting the position of the relay lens 140 along theoptical axis. Hence, the phase distortion corrected pattern H′ (x, y)generated by the LCD 130 can be transmitted to the PAL-SLM 150 at highprecision.

Additionally, the LCD 130 may be replaced by any other type ofelectrically-addressed intensity modulated spatial light modulator. Thespatial light modulator may be either of transmission type or reflectiontype.

The configuration of the PAL-SLM 150 is not limited to the one describedabove. The PAL-SLM 150 can be replaced with any other type ofoptically-addressed phase modulated spatial light modulator havinganother configuration. The optically-addressed phase modulated spatiallight modulator may be either of transmission type or reflection type.

The phase modulation module 40 may be replaced with an type ofelectrically-addressed phase modulated spatial light modulator, atransmission or reflection phase modulation type of liquid-crystaldisplay, or a deformable mirror.

The reading light source 10 may be any other type of laser than a He—Nelaser. The reading light source 10 may be any other light source than alaser.

The writing light source 110 may be any other type of laser beam sourcethan a laser diode. The writing light source 110 may be any other lightsource than a laser diode.

The present invention can be widely applied to phase modulation of lightin laser process apparatuses and laser process method,hologram-reproducing patterns generator and method of generatinghologram-reproducing patterns, and wave-shaping apparatus andwave-shaping method.

1. A computer program recorded on a computer readable recording medium,executed by a computer, comprising: instructions for preparing a desiredphase pattern; instructions for preparing a wavefront-distortioncorrection phase pattern for correcting a wavefront distortion of light;and instructions for adding the desired phase pattern and thewavefront-distortion correction phase pattern to generate a distortioncorrected phase pattern, the wavefront-distortion correction phasepattern including a phase pattern for correcting a wavefront distortioninduced by a phase modulated spatial light modulator.
 2. The computerprogram according to claim 1, wherein the wavefront-distortioncorrection phase pattern includes a phase pattern generated by invertinga sign of a wavefront-distortion phase pattern indicating a wavefrontdistortion induced by an input/output surface of the phase modulatedspatial light modulator.
 3. A computer program recorded on a computerreadable recording medium, executed by a computer, comprising:instructions for preparing a desired phase pattern; instructions forpreparing a wavefront-distortion correction phase pattern for correctinga wavefront distortion of light; and instructions for adding the desiredphase pattern and the wavefront-distortion correction phase pattern togenerate a distortion corrected phase pattern, wherein when a sum of thedesired phase pattern and the wavefront-distortion correction phasepattern has a negative value, or a value equal to or more than 2π, aremainder obtained by dividing the sum by 2π is used as the distortioncorrected phase pattern.
 4. The computer program according to claim 3,wherein the wavefront-distortion correction phase pattern includes aphase pattern generated by inverting a sign of a wavefront distortionphase pattern indicating the wavefront distortion of the light.
 5. Thecomputer program according to claim 3, further comprising instructionsfor storing the wavefront-distortion correction phase pattern, whereinthe instructions for adding reads the wavefront-distortion correctionphase pattern stored by the instructions for storing, and then adds thewavefront-distortion correction phase pattern to the desired phasepattern.
 6. The computer program according to claim 3, furthercomprising instructions for receiving the wavefront-distortioncorrection phase pattern, wherein the instructions for adding adds thereceived wavefront-distortion correction phase pattern to the desiredphase pattern.
 7. A computer program recorded on a computer readablerecording medium, executed by a computer, comprising: instructions forpreparing a desired phase pattern; instructions for preparing awavefront-distortion correction phase pattern for correcting a wavefrontdistortion of light; and instructions for adding the desired phasepattern and the wavefront-distortion correction phase pattern togenerate a distortion corrected phase pattern, the distortion correctedphase pattern being used for driving a reflection type of phasemodulated spatial light modulator.
 8. A computer-readable storage mediumstoring a program executed by a computer for: preparing a desired phasepattern; preparing a wavefront-distortion correction phase pattern forcorrecting a wavefront distortion of light; and adding the desired phasepattern and the wavefront-distortion correction phase pattern togenerate a distortion corrected phase pattern, the wavefront-distortioncorrection phase pattern including a phase pattern for correcting awavefront distortion induced by a phase modulated spatial lightmodulator.
 9. The computer-readable storage medium according to claim 8,wherein when a sum of the desired phase pattern and thewavefront-distortion correction phase pattern has a negative value, or avalue equal to or more than 2π, a remainder obtained by dividing the sumby 2π is used as the distortion corrected phase pattern.
 10. Thecomputer-readable storage medium according to claim 8, wherein the phasemodulated spatial light modulator is a reflection type, and thedistortion corrected phase pattern is used for driving the phasemodulated spatial light modulator.